At first, there were 438 more boys than girls at the stadium. By 4 p.m., a total of 280 boys and girls left the stadium. There were as many boys as girls who left the stadium. In the end, there were 3 times as many boys as girls who remained behind. How many boys were at the stadium at first?
|
Boys |
Girls |
Difference |
Before |
3 u + 140 |
1 u + 140 |
438 |
Change |
- 140 |
- 140 |
|
After |
3 u |
1 u |
2 u |
Since there was the same number of girls and boys that left, the difference between the number of girls and boys remains unchanged.
2 u = 438
1 u = 438 ÷ 2 = 219
Number of boys in the end
= 3 u
= 3 x 219
= 657
Number of boys that left
= 280 ÷ 2
= 140
Number of boys at first
= 657 + 140
= 797
Answer(s): 797