There are 48 apples in three piles. First, take out the apples equal to the number of the second pile from the first pile and merge them into the second pile; then take out the apples equal to the number of the third pile from the second pile and merge them into the third pile; finally, take out the apples equal to the number of the first pile from the third pile and merge them into the first pile

There are 48 apples in three piles. First, take out the apples equal to the number of the second pile from the first pile and merge them into the second pile; then take out the apples equal to the number of the third pile from the second pile and merge them into the third pile; finally, take out the apples equal to the number of the first pile from the third pile and merge them into the first pile

Inverse method
∵ each of the last three piles has: 48 / 3 = 16
Before, there were 16 / 2 = 8 in the first pile and 16 + 8 = 24 in the third pile
The number of the second pile to the third pile: 24 / 2 = 12
At this time, there are 8 in the first pile and 12 in the third pile, so there are 48-8-12 = 28 in the second pile
So in the beginning, the first pile took out 16 to the second pile
The first pile was 8 + 16 = 24
The second pile was 28 / 2 = 14
The third pile had: 48-12-14 = 22
1 2 3
16 16 16
8 16 24
8 28 12
22 14 12

There are three piles of go pieces with the same number. The first pile has the same number of sunspots as the second pile. The third pile has two fifths of all the sunspots

There are as many sunspots in the first pile as there are white ones in the second pile,
The two piles have the same number of pieces
The second pile has as many sunspots as the first pile,
Two piles of sunspots are as many as white ones, each accounting for 1 / 3 of the total number
The third pile of sunspots accounts for two fifths of all sunspots
The rotors of the first and second stacks account for 3 / 5 of all the sunspots
Sunspots in all pieces = 1 / 3 △ 3 / 5 = 5 / 9
White = 1-5 / 9 = 4 / 9
The total number of sunspots is 4 / 9 △ 5 / 9 = 4 / 5

If three quarters of a pile of coal is used, two fifths of the coal will be used, and then there will be [] tons left; if three quarters of a pile of coal is used, two fifths of the coal will be used, and then there will be [] tons left【
Urgent,

Used: 3 / 4 * 2 / 5 = 3 / 10
Three tenths of a ton is used
Remaining: 3 / 4-2 / 5 = 9 / 20
Nine out of twenty tons are left

A pile of 10 tons of coal, used up two fifths, how many tons are left
It's a process

10-10*2/5
=10-4
=6