PSLE
Risa and Penelope folded paper stars over two days. On Wednesday, Risa folded 19 paper stars more than Penelope. On Thursday, Risa folded another 20 paper stars and Penelope folded another 11. At the end of the two days, Risa made ⁷₁₀ of the total number of stars. What was the number of paper stars that Penelope folded?

	Risa	Penelope	Difference
Before	1 u + 19	1 u	19
Change	+ 20	+ 11
After	1 u + 39	1 u + 11	28
Comparing between Risa and Penelope in the end	7 p	3 p	4 p

Difference between the number of paper stars that Risa and Penelope folded in the end is repeated.

Difference between the number of paper stars that Risa and Penelope folded in the end
= 7 p - 3 p
= 4 p

Difference between the number of paper stars that Risa and Penelope folded in the end
= (1 u + 39) - (1 u + 11)
= 1 u + 39 - 1 u - 11
= 39 - 11
= 28

4 p = 28

1 p = 28 ÷ 4 = 7

Number of paper stars that Penelope folded
= 3 p
= 3 x 7
= 21

Answer(s): 21