There are a batch of balls in the pocket, of which red balls account for 37.5%. Later, 12 red balls were put in the pocket, accounting for 75% of the total. Q: How many balls are there in your pocket now?

Solution: Suppose there were x balls before, then there are 37.5%X red balls.

(37.5% X+ 12)/(X+ 12)= 75%

0.375X+ 12=0.75X+9

0.375X=3

X=8

So now there is 8+ 12=20.

There are 20 balls now.

It takes Master Zhang 30 hours to process a batch of parts by himself, and 20 parts in an hour. Now they work together. By the time it was completed, Master Zhang had processed 20% more. Q: How many parts are there in this batch?

Solution: Set *** 100X parts.

Then Li Shifu has already handled (100x-100x * 20%)-2 = 40x.

Processing by Master Zhang 100X-40X=60X.

Li Shifu * * * processing 40X÷20=2X hours.

Then Master Zhang's processing capacity per hour =60X÷2X=30 pieces.

So the total number of parts =30×30=900.

Answer: 900 * * *.

Two cars, A and B, set off from A and B at the same time and walked in opposite directions. It took 65,438+00 hours for A to complete the race, and 65,438+05 hours for B to complete the race. After the two cars met on the way, A traveled another 96 kilometers, which is 80% of A's total journey. Q: How many kilometers is it between A and B?

Solution:

The speed ratio of Party A and Party B = 15: 10=3:2.

So when they met, A walked 3/(3+2)=60% of the whole journey.

After 96 kilometers, 80% of the whole journey was completed.

So 96 kilometers is 20% of the whole journey.

Total length = 96 ÷ 20% = 480km.

A: AB is 480 kilometers apart.