PSLE
Bobby had 8 boxes of beads. At first, each of the boxes contained the same number of beads. He took 20 beads from each box. After that, the total number of beads left in the 8 boxes was equal to the total number of beads in 3 of the boxes at first. What was the number of beads in each box at first?

	3 boxes at first	Total boxes in the end
Number	3	8
Value	1 u + 20	1 u
Total value	3 u + 60	8 u

Number of beads in each box in the end = 1 u
Number of beads in each box at first = 1 u + 20

Number of beads in 3 boxes at first 
= 3 x (1 u + 20)
= 3 u + 60

Total number of beads left in the 8 boxes was equal to total number of beads in 3 boxes at first.

8 u = 3 u + 60 
8 u - 3 u = 60
5 u = 60

1 u = 60 ÷ 5 = 12

Number of beads in each box at first
= 1 u + 20
= 12 + 20
= 32

Answer(s): 32