Samuel's school organized a trip to Fiji. At first, the ratio of the number of girls to the number of boys who planned to participate in the trip was 8 : 7. On the day of registration, 15 boys decided to withdraw and 15 more girls decided to join in. In the end, the number of boys who participated became 30% of the total children for the trip. How many more girls than boys would visit Fiji in the end?

	Girls	Boys	Total
Before	8x2 = 16 u	7x2 = 14 u	15x2 = 30 u
Change	+ 5 u	- 5 u
After	7x3 = 21 u	3x3 = 9 u	10x3 = 30 u

30% = ³⁰₁₀₀ = ³₁₀

Since 15 boys withdrew and another 15 girls joined, the total number of children  at first and in the end remains unchanged. Make the total number of children the same. LCM of 15 and 10 is 30.

Number of boys who decided to withdraw
= 14 u - 9 u
= 5 u

5 u = 15

1 u = 15 ÷ 5 = 3

Number of more girls than boys in the end
= 21 u - 9 u
= 12 u
= 12 x 3
= 36

Answer(s): 36