Solving an elementary school math problem can only be done by adding or subtracting

Four hours: Don't know the algorithm! Paying attention! I don't know what kind of answer is acceptable! Here's my algorithm:

The distance in one hour by car is 60 (km).

The distance traveled by bicycle per hour is 15 (km).

An hour away by car, it takes x hours for a bicycle to complete:

60-15=45 x-1

45-15=30 x-1-1

30-15=15 y-1-1-1

15-15=0 x-1-1-1-1=0

Then x=1+1+1+1=4

In fact, the primary school question restricts the number of times a car travels per hour to an integer multiple of the distance traveled by a bicycle. If it's not an integer multiple, then it's a multiplier of the difficulty!

The car traveled 60 kilometers in 1 hour 60-15=45 45-15=30 30-15=15 15-15=0 minus 4 times, so it takes 4 hours or 60-15-15-15-15=0 minus 4 15 to get the answer.

We divide 60 into 15+15+15+15, and a bicycle travels exactly 15 kilometers per hour, so the car runs for 1 hour, and the bicycle travels for 4 hours.

Car: 60 km/h; 60

Cycling: 15 kilometers per hour. 15+15+15+15=60 so it's 4 hours.

The car travels 60 kilometers in an hour, and the bicycle travels 15 kilometers per hour, so.

So it takes 4 hours for a bicycle to travel 1 hour by car.

Let's say, if it's really a question for elementary school students, the addition is definitely unreasonable, and subtraction should be used, and it's best to subtract little by little!

You can use 60 to subtract 15 in turn, and finally see how many 15 you have in total, and how many hours it will take.

The car runs 60 kilometers in 1 hour, and 60 kilometers divided by 15 equals 4, so it takes 4 hours.

This problem can be solved using addition and subtraction in the first grade of elementary school. We can use the concept of "difference" to solve the problem.

Let the ** of watermelon be X yuan.

According to the title, Xiao Ming's ** buying watermelon is 8 yuan cheaper than Xiaohong, that is, Xiao Ming's ** buying watermelon is X-8 yuan, and Xiaohong's buying watermelon ** is X-6 yuan. And the ** of the two people who buy watermelon together is 3 yuan cheaper than they buy alone, that is, the ** bought together is 2x-3 yuan.

Therefore, we can list the following equations for Sou Kuanxiang:

x-8）+（x-6）=（2x-3）

Simplify the equation to get:

2x-14=2x-3

By adding and destroying the subtraction operation, we can get:

This is not true, because the left and right sides are not equal. Therefore, we cannot solve this problem with addition and subtraction in the first grade of primary school. It requires the use of higher-level mathematical knowledge, such as algebraic equations, to solve.

There are 40 people in total.

Analysis: Every two people shake hands, Xiaohong shakes hands 39 times, indicating that 39 people have shaken hands with Xiaohong. In Xiaohong's "shaking hands every two people" activity, the relationship between the number of people is:

The same person who has shaken hands 39 times is Xiaohong: 1 person who has only shaken Xiaohong's hand once is 39 people.

There are 40 people in total.

40 shake hands every two Xiaohong has to shake hands with everyone except herself, so there are 39 people besides Xiaohong, a total of 39+1 40 people.

Solution: The number of qualified parts produced by Master Zhang in the past two months is:

180x95%+240x90%=171+216=387 Therefore, the pass rate of Master Zhang's production parts in these two months is about:

387÷(180+240)x100%=387÷420x100%≈92%

Answer: Master Zhang's pass rate of the parts produced in the past two months is about 92%.

Squared * 20 = 1570

squared * 17=

Question 2. radius = 9 2=

Square * third problem solution: **x yuan.

x=120

This number is envied.

Minus + difference = 98 2 = 49, meiotic brother noisy - difference = 21, so (minus + difference) + (minus - difference) = 49 + 21 minus = 35, difference touch code = 14, this subtraction is: 49-35 = 14.

Suppose that a 5-ton truck transports x trips in total 0 then: a 3-ton truck needs to transport (59-5*x) 3

Total shipping fee = x * 150 + ((59-5 * x) 3) * 96 = 1888-10 * x

From this formula, the larger the x, the less the total shipping cost.

Because the value of (59-5*x) 3 must be an integer and cannot be rounded, if there is a decimal place.

So: x takes the value of 10

That is: total shipping = 1788 yuan.

To make the total carrying capacity = 59, because the average freight per ton of large trucks is the least, so give priority to large trucks, so that the amount of goods left after the large trucks are transported is just enough to fill all the small trucks, so it is best to use 10 large and 3 small trucks, 10 150 + 3 96 = 1788 (yuan).

First of all, it can be determined that the freight per ton of goods is lower than that of small trucks, and then when comparing 9 tons of goods, large trucks need 2 trips, costing 300 yuan, small trucks need 3 trips, costing 288 yuan, and the combination of large and small trucks is more uneconomical, so the answer is 10 150 + 3 96

It is most economical to use 10 large trucks and 3 small trucks, a total of 150 10 96 3 = 1788 (yuan).

8400 1000 3 = about equal to 3 3 * 300 = 900 yuan 8400 about equal to 3 3 * 330 = 990 yuan 8400 1000 about equal to 2 2 * 380 = 760 yuan Therefore, it is most cost-effective to use a deadweight ton car.

The two trucks are the most cost-effective and the lowest freight.

A deadweight ton, freight 380 yuan. The most advantageous.

The first type costs 900 yuan for three cars, the second type costs 990 yuan for three cars, and the third type costs 2 cars for 760 yuan.

Tons = 3500 kg Tons = 4500 kg I pushed it for a long time before I knew that 380 = 380 was the most cost-effective.