PSLE
In a school, 30% of the members in Computer Club and 40% of the members in Art Club are boys. Both clubs have the same number of girls. The Computer Club has 10 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	3x3	7x3	2x7	3x7
Comparing the girls in 2 clubs		1		1
	9 u	21 u	14 u	21 u

30% = ³⁰₁₀₀ = ³₁₀

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

40% = ⁴⁰₁₀₀ = ²₅

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

The number of girls in both clubs is the same. Make the numerators the same. LCM of 7 and 3 is 21. 

7x310x3 of the members in Computer Club = 3x75x7 of the members in Art Club
2130of the members in Computer Club = 2135 of the members in Art Club

Number of less boys in Computer Club than Art Club
= 14 u - 9 u
= 5 u

5 u = 10

1 u = 10 ÷ 5 = 2

Number of members in Art Club
= 35 u
= 35 x 2
= 70

Answer(s): 70