PSLE
Usha and Wendy folded paper balls over two days. On Thursday, Usha folded 25 paper balls more than Wendy. On Friday, Usha folded another 39 paper balls and Wendy folded another 16. At the end of the two days, Usha made ⁷₁₀ of the total number of balls. What was the number of paper balls that Wendy folded?

	Usha	Wendy	Difference
Before	1 u + 25	1 u	25
Change	+ 39	+ 16
After	1 u + 64	1 u + 16	48
Comparing between Usha and Wendy in the end	7 p	3 p	4 p

Difference between the number of paper balls that Usha and Wendy folded in the end is repeated.

Difference between the number of paper balls that Usha and Wendy folded in the end
= 7 p - 3 p
= 4 p

Difference between the number of paper balls that Usha and Wendy folded in the end
= (1 u + 64) - (1 u + 16)
= 1 u + 64 - 1 u - 16
= 64 - 16
= 48

4 p = 48

1 p = 48 ÷ 4 = 12

Number of paper balls that Wendy folded
= 3 p
= 3 x 12
= 36

Answer(s): 36