Mia's school organized a trip to Peru. 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, 35 boys decided to withdraw and 35 more girls decided to join in. In the end, the number of boys who participated became 35% of the total children for the trip. How many children would visit Peru in the end?

	Girls	Boys	Total
Before	8x4 = 32 u	7x4 = 28 u	15x4 = 60 u
Change	+ 7 u	- 7 u
After	13x3 = 39 u	7x3 = 21 u	20x3 = 60 u

35% = ³⁵₁₀₀ = ⁷₂₀

Since 35 boys withdrew and another 35 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 20 is 60.

Number of boys who decided to withdraw
= 28 u - 21 u
= 7 u

7 u = 35

1 u = 35 ÷ 7 = 5

Number of children that would visit Peru in the end
= 39 u + 21 u
= 60 u
= 60 x 5
= 300

Answer(s): 300