PSLE
Mary and Tammy folded paper balls over two days. On Wednesday, Mary folded 10 paper balls more than Tammy. On Thursday, Mary folded another 37 paper balls and Tammy folded another 11. At the end of the two days, Mary made ⁷₁₀ of the total number of balls. What was the number of paper balls that Tammy folded?

	Mary	Tammy	Difference
Before	1 u + 10	1 u	10
Change	+ 37	+ 11
After	1 u + 47	1 u + 11	36
Comparing between Mary and Tammy in the end	7 p	3 p	4 p

Difference between the number of paper balls that Mary and Tammy folded in the end is repeated.

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

Difference between the number of paper balls that Mary and Tammy folded in the end
= (1 u + 47) - (1 u + 11)
= 1 u + 47 - 1 u - 11
= 47 - 11
= 36

4 p = 36

1 p = 36 ÷ 4 = 9

Number of paper balls that Tammy folded
= 3 p
= 3 x 9
= 27

Answer(s): 27