There were 5 more boys than girls in the computer lab. Excluding 8 girls, the number of girls was ⁴₅ of the number of boys. When another 7 boys joined, what fraction of the pupils were boys in the end? Give your answer in its simplest form.

	Boys	Girls
Comparing boys  and girls at first	5 more
Before	5 u	4 u + 8
Change	+ 7
After	5 u + 7	4 u + 8

Number of boys at first was 5 more than the number of girls. If another 5 girls entered the computer lab at first, the number of boys and girls at first would be the same.

5 u = 4 u + 8 + 5 
5 u - 4 u = 8 + 5

1 u = 13

Total number of boys in the end
= 5 u + 7
= 5 x 13 + 7
= 65 + 7
= 72

Total number of pupils in the end
= 5 u + 7 + 4 u + 8
= 9 u + 15
= 9 x 13 + 15
= 132

Fraction of the pupils who were boys in the end
= ⁷²₁₃₂
= ⁶₁₁

Answer(s): ⁶₁₁