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

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

70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of the members in Art Club that are boys
= 1 - ⁷₁₀
= ³₁₀

80% = ⁸⁰₁₀₀ = ⁴₅

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

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

3x110x1 of the members in Art Club = 1x35x3 of the members in Computer Club
310of the members in Art Club = 315 of the members in Computer Club

Number of more girls in Computer Club than Art Club
= 12 u - 7 u
= 5 u

5 u = 25

1 u = 25 ÷ 5 = 5

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

Answer(s): 95