Russia and Chile took part in Youth Games. From Russia, the ratio of the number of female supporters to the number of male supporters was 3 : 4. From Chile, the ratio of the number of female supporters to the number of male supporters was 1 : 4. The total number of supporters from Russia was ⁷₂₀ the total number of supporters from Chile.

1. What was the ratio of the number of female supporters from Russia to the total number of female supporters from both countries? Express the answer in the simplest form.
2. After 16 female supporters from both countries left the games, the percentage of all the male supporters became 80%. How many more male supporters from Chile than Russia were there at first?

Russia		Chile
7 u		20 u
Female supporters	Male supporters	Female supporters	Male supporters
3	4	1x2	4x2
3 u	4 u	4 u	16 u

(a)
Number of female supporters from Chile
= ¹₅ x 20 u
= 4 u

Number of male supporters from Russia
= ⁴₅ x 20 u
= 16 u

Total number of female supporters
= 3 u + 4 u
= 7 u

Female supporters from Russia : Total female supporters
3 : 7

(b)

	Female supporters	Male supporters
Before	7x4 = 28%	20x4 = 80%
Change	- 16
After	20%	80%

Number of female supporters in the end in percent
= 100% - 80%
= 20%

Total number of male supporters at first
= 4 u + 16 u
= 20 u

After 16 female supporters from both countries left the games, the percentage of all the male supporters became 80%.

Since only female supporters left the games, the number of male supporters remains unchanged. Make the number of male supporters the same.

20 u = 80%

1 u = 80% ÷ 20 = 4%

Number of female supporters at first in percent
= 7 x 4%
= 28%

Number of female supporters from both countries who left
= 28% - 20%
= 8%

8% = 16 

1% = 16 ÷ 8 = 2

Number of more male supporters from Chile than Russia at first
= 16 u - 4 u
= 12 u
= 12 x 4%
= 48%
= 48 x 2
= 96 

Answer(s): (a) 3 : 7; (b) 96