PSLE
Irene and Xandra folded paper balls over two days. On Wednesday, Irene folded 25 paper balls more than Xandra. On Thursday, Irene folded another 17 paper balls and Xandra folded another 2. At the end of the two days, Irene made ⁷₉ of the total number of balls. What was the number of paper balls that Irene folded?

	Irene	Xandra	Difference
Before	1 u + 25	1 u	25
Change	+ 17	+ 2
After	1 u + 42	1 u + 2	40
Comparing between Irene and Xandra in the end	7 p	2 p	5 p

Difference between the number of paper balls that Irene and Xandra folded in the end is repeated.

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

Difference between the number of paper balls that Irene and Xandra folded in the end
= (1 u + 42) - (1 u + 2)
= 1 u + 42 - 1 u - 2
= 42 - 2
= 40

5 p = 40

1 p = 40 ÷ 5 = 8

Number of paper balls that Irene folded
= 7 p
= 7 x 8
= 56

Answer(s): 56