At first, there were 396 more girls than boys at the zoo. By 2 p.m., a total of 258 girls and boys left the zoo. There were as many girls as boys who left the zoo. In the end, there were 5 times as many girls as boys who remained behind. How many girls were at the zoo at first?
| |
Girls |
Boys |
Difference |
| Before |
5 u + 129 |
1 u + 129 |
396 |
| Change |
- 129 |
- 129 |
|
| After |
5 u |
1 u |
4 u |
Since there was the same number of boys and girls that left, the difference between the number of boys and girls remains unchanged.
4 u = 396
1 u = 396 ÷ 4 = 99
Number of girls in the end
= 5 u
= 5 x 99
= 495
Number of girls that left
= 258 ÷ 2
= 129
Number of girls at first
= 495 + 129
= 624
Answer(s): 624
