PSLE
In a school, 70% of the members in Dancing Club and 80% of the members in Singing Club are boys. Both clubs have the same number of girls. The Singing Club has 25 more boys than the Dancing Club. How many boys are there altogether?

	Dancing Club		Singing Club
Types	Boys	Girls	Boys	Girls
Comparing the boys and the girls in each club	7x1	3x1	4x3	1x3
Comparing the girls in 2 clubs		1		1
	7 u	3 u	12 u	3 u

70% = ⁷⁰₁₀₀ = ⁷₁₀

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

80% = ⁸⁰₁₀₀ = ⁴₅

Fraction of the members in Singing club that are girls
= 1 - ⁴₅
= ¹₅

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

3x110x1 of the members in Dancing Club = 1x35x3 of the members in Singing Club
310of the members in Dancing Club = 315 of the members in Singing Club

Number of more boys in Singing Club than Dancing Club
= 12 u - 7 u
= 5 u

5 u = 25

1 u = 25 ÷ 5 = 5

Total number of boys
= 7 u + 12 u
= 19 u
= 19 x 5
= 95

Answer(s): 95