At first, there were 390 more girls than boys at the theme park. By 3 p.m., a total of 230 girls and boys left the theme park. There were as many girls as boys who left the theme park. In the end, there were 4 times as many girls as boys who remained behind. How many girls were at the theme park at first?
| |
Girls |
Boys |
Difference |
| Before |
4 u + 115 |
1 u + 115 |
390 |
| Change |
- 115 |
- 115 |
|
| After |
4 u |
1 u |
3 u |
Since there was the same number of boys and girls that left, the difference between the number of boys and girls remains unchanged.
3 u = 390
1 u = 390 ÷ 3 = 130
Number of girls in the end
= 4 u
= 4 x 130
= 520
Number of girls that left
= 230 ÷ 2
= 115
Number of girls at first
= 520 + 115
= 635
Answer(s): 635
