PSLE
In a school, 40% of the members in Computer Club and 60% of the members in Art Club are girls. Both clubs have the same number of boys. The Computer Club has 35 less girls than the Art Club. How many members are there in Art Club?

	Computer Club		Art Club
Types	Girls	Boys	Girls	Boys
Comparing the girls and the boys in each club	2x2	3x2	3x3	2x3
Comparing the boys in 2 clubs		1		1
	4 u	6 u	9 u	6 u

40% = ⁴⁰₁₀₀ = ²₅

Fraction of the members in Computer Club that are boys
= 1 - ²₅
= ³₅

60% = ⁶⁰₁₀₀ = ³₅

Fraction of the members in Art club that are boys
= 1 - ³₅
= ²₅

The number of boys in both clubs is the same. Make the numerators the same. LCM of 3 and 2 is 6. 

3x25x2 of the members in Computer Club = 2x35x3 of the members in Art Club
610of the members in Computer Club = 615 of the members in Art Club

Number of less girls in Computer Club than Art Club
= 9 u - 4 u
= 5 u

5 u = 35

1 u = 35 ÷ 5 = 7

Number of members in Art Club
= 15 u
= 15 x 7
= 105

Answer(s): 105