Math problems, with the help of the 6th grade, add 50 points if you are right

1.A is x B is x + x = 40 40 and 322, used to do 1200 8 = 150 per hour, now do 1200 per hour 6 = 200

3. Girl x Boy 2x 3 2x 3 +1= x = 30 Girl 30 Boy 20 at the beginning and then the total 514, this question is ambiguous Look at how to understand it Two days of labor sold That is, the remaining This is 35q kg 35 and the last 175 kg.

There is also an understanding that what is sold on the second day is the remainder of the first day, that is, this is the total sold and the remaining unsold total = 35 kg.

Both of the above algorithms are possible to see exactly what the questioner means.

8 * Party B Party A = 400 Both sides Divide to get Party B - Party A = 500 Party B + Party A = 14400

Binary one-time inequality solution Party B's deposit = 7450 Party A's deposit = 6950

1.You can set A as x and B as y, then there is.

x+y= solves this system of binary equations to get x=4,y=

2. The time taken to produce each part in the past can be set to x, and the time taken to produce each part is y now.

1200x=8

1200y=6

The solution is x=8 1200, y=6 1200

Then (x-y) x=

As a result, productivity per hour has increased by 25%.

1. Question A is 4, it is already a matter of time, and the others think about themselves.

There are x books in total.

5/8x-10=3/8x+10-4

x = 64 assumes the original storage of x tons of apples.

1-2/5）x+x=

Then the upper layer turns out to be 10*2 -4= 16 more than the lower layer.

There are 16 (5 8 - 3 8) = 64 copies.

1. Set up a total of x copies.

3/8x+10)-(5/8x-10)=4x=64

2. Set the original Apple X

3/5x+x=

1 is set to x, and then the column sub 5 8 x -10 =3 8 x +10 -4

Solved 24 copies.

2 Let there be x and then the column formula x-3 5x+ to get 22 tons.

1. [2+2/5) +1+1/3) ×5]÷(3+2/5）-（1+ 1/3）=[12/5+20/3]÷(17/5)-4/3

4 (6 6 7 - 3 9 13) (3 3 7 - 2 2 11) 2 7 13

5 7 9 * 4 and 17 20 5 18 - 3 and 3 5 +6 and 3 20 * 3 and 3 5).

1.[2 2 5) +1 1 3) *5] divided by (3 2 5) - (1 1 3).

12 5) +20 3) ] divided by (17 5) - (4 3).

1 and 1 3

4.(6 6 7 - 3 9 13) (3 3 7 - 2 2 11) 2 7 13

(6 6 7 - 3 9 13) (3 3 7 - 2 2 11) 2 7 13

15.7 9 * 4 again 17 20 5 18 - 3 again 3 5 +6 again 3 20 * 3 again 3 5).

7 9 * 4 again 17 20 5 18 - 3 again 3 5 +6 again 3 20 * 3 again 3 5).

Dead count) 2Original = 1-1 81 = 801 (split item).

3.Original formula = 1 1 * 3 + 1 3 * 5 + 1 5 * 7 + 1 7 * 9 + 1 9 * 11 + 1 11 * 13 = 1 2 * (1-1 13) = 6 13 (split item).

4.Original = (48 7-48 13) (24 7-24 13)*13 33=2*13 33=26 33

5.Original formula = 7 9 * (97 20 * 18 5-18 5 + 123 20 * 18 5) = 7 9 * [18 5 * (97 20-1 + 123 20)] = 7 9 * [18 5 * 10] = 7 9 * 36 = 28

So longing. The process is as follows:

1.Original = (12 5 + 4 3 * 5) * 5 17-4 3

2.Before I do this question, let me tell you a rule::

1 [n*(n+a)]=(1 a)*[1 n-1 (n+a)], where a is an integer. So in this question, a=4That's good to do :

Original = 1 (1*3)+1 (3*5)+1 (5*7)+1 (7*9)+1 (9*11)+1 (11*13).

4.Before I do this, I still have to write a formula:

n/a-n/b=n*(b-a)/(ab)

From the above formula: original = (48 7-48 13) (24 7-24 11) (33 13).

Approximate points yield: original = 1

5.Original formula = 7 9 * [(97 20) * (18 5) -18 5 + (123 * 18) (20 * 5)].

2.The problem is: from n=1 to 77, sum 4 n(n+4).

4/n(n+4)=1/n-1/（n+4）。That is, the original question is (1+1 2+1 3+..)1/77)-(1/5+1/6+1/7+..