PSLE
Elijah had 5 jars of balls. At first, each of the jars contained the same number of balls. He took 13 balls from each jar. After that, the total number of balls left in the 5 jars was equal to the total number of balls in 4 of the jars at first. What was the number of balls in each jar at first?

	4 jars at first	Total jars in the end
Number	4	5
Value	1 u + 13	1 u
Total value	4 u + 52	5 u

Number of balls in each jar in the end = 1 u
Number of balls in each jar at first = 1 u + 13

Number of balls in 4 jars at first 
= 4 x (1 u + 13)
= 4 u + 52

Total number of balls left in the 5 jars was equal to total number of balls in 4 jars at first.

5 u = 4 u + 52 
5 u - 4 u = 52
1 u = 52

1 u = 52 ÷ 1 = 52

Number of balls in each jar at first
= 1 u + 13
= 52 + 13
= 65

Answer(s): 65