PSLE
In a school, 60% of the members in Singing Club and 80% of the members in Dancing Club are girls. Both clubs have the same number of boys. The Singing Club has 55 less girls than the Dancing Club. How many members are there in Dancing Club?

	Singing Club		Dancing Club
Types	Girls	Boys	Girls	Boys
Comparing the girls and the boys in each club	3x1	2x1	4x2	1x2
Comparing the boys in 2 clubs		1		1
	3 u	2 u	8 u	2 u

60% = ⁶⁰₁₀₀ = ³₅

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

80% = ⁸⁰₁₀₀ = ⁴₅

Fraction of the members in Dancing club that are boys
= 1 - ⁴₅
= ¹₅

The number of boys in both clubs is the same. Make the numerators the same. LCM of 2 and 1 is 2. 

2x15x1 of the members in Singing Club = 1x25x2 of the members in Dancing Club
25of the members in Singing Club = 210 of the members in Dancing Club

Number of less girls in Singing Club than Dancing Club
= 8 u - 3 u
= 5 u

5 u = 55

1 u = 55 ÷ 5 = 11

Number of members in Dancing Club
= 10 u
= 10 x 11
= 110

Answer(s): 110