PSLE
In a school, 40% of the members in Dancing Club and 60% of the members in Singing Club are girls. Both clubs have the same number of boys. The Dancing Club has 50 less girls than the Singing Club. How many members are there in Singing Club?

	Dancing Club		Singing 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 Dancing Club that are boys
= 1 - ²₅
= ³₅

60% = ⁶⁰₁₀₀ = ³₅

Fraction of the members in Singing 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 Dancing Club = 2x35x3 of the members in Singing Club
610of the members in Dancing Club = 615 of the members in Singing Club

Number of less girls in Dancing Club than Singing Club
= 9 u - 4 u
= 5 u

5 u = 50

1 u = 50 ÷ 5 = 10

Number of members in Singing Club
= 15 u
= 15 x 10
= 150

Answer(s): 150