At first, there were 406 more boys than girls at the concert hall. By 3 p.m., a total of 254 boys and girls left the concert hall. There were as many boys as girls who left the concert hall. In the end, there were 3 times as many boys as girls who remained behind. How many boys were at the concert hall at first?
|
Boys |
Girls |
Difference |
Before |
3 u + 127 |
1 u + 127 |
406 |
Change |
- 127 |
- 127 |
|
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 = 406
1 u = 406 ÷ 2 = 203
Number of boys in the end
= 3 u
= 3 x 203
= 609
Number of boys that left
= 254 ÷ 2
= 127
Number of boys at first
= 609 + 127
= 736
Answer(s): 736