PSLE
In a school, 50% of the members in Drama Club and 70% of the members in Reading Club are girls. Both clubs have the same number of boys. The Drama Club has 12 less girls than the Reading Club. How many members are there in Reading Club?

	Drama Club		Reading Club
Types	Girls	Boys	Girls	Boys
Comparing the girls and the boys in each club	1x3	1x3	7x1	3x1
Comparing the boys in 2 clubs		1		1
	3 u	3 u	7 u	3 u

50% = ⁵⁰₁₀₀ = ¹₂

Fraction of the members in Drama Club that are boys
= 1 - ¹₂
= ¹₂

70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of the members in Reading club that are boys
= 1 - ⁷₁₀
= ³₁₀

The number of boys in both clubs is the same. Make the numerators the same. LCM of 1 and 3 is 3. 

1x32x3 of the members in Drama Club = 3x110x1 of the members in Reading Club
36of the members in Drama Club = 310 of the members in Reading Club

Number of less girls in Drama Club than Reading Club
= 7 u - 3 u
= 4 u

4 u = 12

1 u = 12 ÷ 4 = 3

Number of members in Reading Club
= 10 u
= 10 x 3
= 30

Answer(s): 30