PSLE
Usha and Barbara folded paper balls over two days. On Wednesday, Usha folded 54 paper balls more than Barbara. On Thursday, Usha folded another 39 paper balls and Barbara folded another 18. At the end of the two days, Usha made ⁷₉ of the total number of balls. What was the number of paper balls that Usha folded?

	Usha	Barbara	Difference
Before	1 u + 54	1 u	54
Change	+ 39	+ 18
After	1 u + 93	1 u + 18	75
Comparing between Usha and Barbara in the end	7 p	2 p	5 p

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

Difference between the number of paper balls that Usha and Barbara folded in the end
= 7 p - 2 p
= 5 p

Difference between the number of paper balls that Usha and Barbara folded in the end
= (1 u + 93) - (1 u + 18)
= 1 u + 93 - 1 u - 18
= 93 - 18
= 75

5 p = 75

1 p = 75 ÷ 5 = 15

Number of paper balls that Usha folded
= 7 p
= 7 x 15
= 105

Answer(s): 105