PSLE
Betty and Winnie folded paper cranes over two days. On Tuesday, Betty folded 33 paper cranes more than Winnie. On Wednesday, Betty folded another 40 paper cranes and Winnie folded another 21. At the end of the two days, Betty made ⁷₁₀ of the total number of cranes. What was the number of paper cranes that Winnie folded?

	Betty	Winnie	Difference
Before	1 u + 33	1 u	33
Change	+ 40	+ 21
After	1 u + 73	1 u + 21	52
Comparing between Betty and Winnie in the end	7 p	3 p	4 p

Difference between the number of paper cranes that Betty and Winnie folded in the end is repeated.

Difference between the number of paper cranes that Betty and Winnie folded in the end
= 7 p - 3 p
= 4 p

Difference between the number of paper cranes that Betty and Winnie folded in the end
= (1 u + 73) - (1 u + 21)
= 1 u + 73 - 1 u - 21
= 73 - 21
= 52

4 p = 52

1 p = 52 ÷ 4 = 13

Number of paper cranes that Winnie folded
= 3 p
= 3 x 13
= 39

Answer(s): 39