At first, there were 425 more girls than boys at the zoo. By 1 p.m., a total of 220 girls and boys left the zoo. There were as many girls as boys who left the zoo. In the end, there were 6 times as many girls as boys who remained behind. How many girls were at the zoo at first?
| |
Girls |
Boys |
Difference |
| Before |
6 u + 110 |
1 u + 110 |
425 |
| Change |
- 110 |
- 110 |
|
| After |
6 u |
1 u |
5 u |
Since there was the same number of boys and girls that left, the difference between the number of boys and girls remains unchanged.
5 u = 425
1 u = 425 ÷ 5 = 85
Number of girls in the end
= 6 u
= 6 x 85
= 510
Number of girls that left
= 220 ÷ 2
= 110
Number of girls at first
= 510 + 110
= 620
Answer(s): 620
