2 math problems, I hope you will solve them! Write about the process, and why you do it

% is 1/5, however, 1 part is salt, 5 parts is salt water, 5-1 is water, water is 4, salt is 1, salt is less than water (4-1) 4 = 75%.

2. If the distance is regarded as the unit "1", the original speed is 1/10, and the current speed is 1/8, how much has it improved, that is, 1/8 - 1/10 = 1/40. Just use 1/40 1/10 = 1/4 hope.

1) Water: 1-20%=80%.

Less salt than water: (80%-20%) 80%.

2) Original speed: 1 10 total distance per minute, later speed: 1 8 total distance per minute.

After that, you should divide the later velocity by the original velocity, i.e.

1. The salt content is 20%, which means that water accounts for 1-20%=80%, so the salt is less than water (80%-20%) 1-20%) = 75%.

2. Regard the distance as a unit "1", the original speed is 1 10, and the current speed is 1 8, how much has it improved, that is.

1) In brine with a salt content of 20, the salt is less than that of water [75%].

20 parts salt, 80 parts water. （80-20）÷80=75%

2) The time it takes for Xiaoqing to walk from home to school has been reduced from 10 minutes to 8 minutes, and Xiaoqing's walking speed has increased by [25%].

20% salt, 80% water, less salt than water: (80%-20%) 80 %=75%.

The time ratio is: 5:4, then the speed ratio is: 4:5, because the distance is the same. Increase: (5-4) 4=25%.

One part minus one tenth.

1, (x + y) with fiber 2 = slag hidden defeat x3 +2 y) 5 = + = 17 to get x = 19 years = 14

2, the public is like a shudder to travel 1 2, the truck walks 1 2 - 1 6 = 1 3 is less than the travel speed of the two cars is 3:2

Then the remaining 1 6 passengers walk 1 6 3 5 = 1 10, so 1 2 + 1 10 = 3 5 of the entire bus

Two physics questions, solved.

If you have any academic questions, you can use the "one-on-one online Q&A".

1.Since it is filled with water, then the volume of the water is v=8 5 2 80m The distance between the water surface and the cylinder mouth can be set to x, then the volume of water in the tank is: 5 5 (5-x)=80m

It can be solved that x= that is, the distance between the water surface and the cylinder mouth is.

2.The second question is to see how to cut, in which direction to cut, if you cut on the length of the cuboid, then:

Cut a knife: add two surfaces on the previous basis, the area is equal to 2 2 = 4, then add two additional surfaces to 8

Cut two knives: add four surfaces to the previous one, increasing the surface area by: 4 4 = 16

1. The volume is equal, the volume is 8 * 5 * 2 = 80, and the height is 80 5 5 = meters.

2. The original surface area is 2 * (8 * 2 + 2 * 2 + 8 * 2) = 72 square meters, and it is good to cut a knife.

m2There are 3 answers, n represents the number of knives cut, which are:

2x8nx2

2x2nx2

(1) 8*5*2 (5*5)=16 5,5-16 5=9 5, so 9 5 = meters from the cylinder port.

2) add 32 square meters or 8 square meters; Add 64 square meters or 16 square meters. (Strictly speaking, the increased surface area is uncertain, depending on the cross-cutting, vertical-cutting, or oblique cutting, and the degree of oblique cutting will also have different surface area cut.) ）

<> such as a frank touch of socks let the excitement be noisy.

5 8 cups orange juice 1 8 cups water.

The water added should be 1 4 cups, and at the end half of it was drunk, so drink 1 8 cups of water. I drank 1 4 cups of orange juice first, left 3 4 cups, and then drank half of it, i.e. 3 8 cups, so 1 4 + 3 8 = 5 8 cups of orange juice.