PSLE
In a school, 60% of the members in Dancing Club and 70% of the members in Singing Club are boys. Both clubs have the same number of girls. The Dancing Club has 10 less boys than the Singing Club. How many members are there in Singing Club?

	Dancing Club		Singing Club
Types	Boys	Girls	Boys	Girls
Comparing the boys and the girls in each club	3x3	2x3	7x2	3x2
Comparing the girls in 2 clubs		1		1
	9 u	6 u	14 u	6 u

60% = ⁶⁰₁₀₀ = ³₅

Fraction of the members in Dancing Club that are girls
= 1 - ³₅
= ²₅

70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of the members in Singing club that are girls
= 1 - ⁷₁₀
= ³₁₀

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

2x35x3 of the members in Dancing Club = 3x210x2 of the members in Singing Club
615of the members in Dancing Club = 620 of the members in Singing Club

Number of less boys in Dancing Club than Singing Club
= 14 u - 9 u
= 5 u

5 u = 10

1 u = 10 ÷ 5 = 2

Number of members in Singing Club
= 20 u
= 20 x 2
= 40

Answer(s): 40