PSLE
In a school, 30% of the members in Computer Club and 80% of the members in Art Club are boys. Both clubs have the same number of girls. The Computer Club has 125 less boys than the Art Club. How many members are there in Art Club?

	Computer Club		Art Club
Types	Boys	Girls	Boys	Girls
Comparing the boys and the girls in each club	3x1	7x1	4x7	1x7
Comparing the girls in 2 clubs		1		1
	3 u	7 u	28 u	7 u

30% = ³⁰₁₀₀ = ³₁₀

Fraction of the members in Computer Club that are girls
= 1 - ³₁₀
= ⁷₁₀

80% = ⁸⁰₁₀₀ = ⁴₅

Fraction of the members in Art club that are girls
= 1 - ⁴₅
= ¹₅

The number of girls in both clubs is the same. Make the numerators the same. LCM of 7 and 1 is 7. 

7x110x1 of the members in Computer Club = 1x75x7 of the members in Art Club
710of the members in Computer Club = 735 of the members in Art Club

Number of less boys in Computer Club than Art Club
= 28 u - 3 u
= 25 u

25 u = 125

1 u = 125 ÷ 25 = 5

Number of members in Art Club
= 35 u
= 35 x 5
= 175

Answer(s): 175