The number of girls in the lecture hall was
57 that of the boys. There were 104 more boys than girls. After some boys had left the lecture hall, the number of girls at the lecture hall was five times the number of the remaining boys. How many boys left the lecture hall?
|
Boys |
Girls |
Difference |
Before |
7 u |
5 u |
2 u |
Change |
- ? |
|
|
After |
1 u |
5 u |
|
The number of girls at first and in the end remains unchanged.
Number of more boys than girls at first
= 7 u - 5 u
= 2 u
2 u = 104
1 u = 104 ÷ 2 = 52
Number of boys that left
= 7 u - 1 u
= 6 u
= 6 x 52
= 312
Answer(s): 312