The number of girls in the lecture theatre was
49 that of the boys. There were 150 more boys than girls. After some boys had left the lecture theatre, the number of girls at the lecture theatre was four times the number of the remaining boys. How many boys left the lecture theatre?
|
Boys |
Girls |
Difference |
Before |
9 u |
4 u |
5 u |
Change |
- ? |
|
|
After |
1 u |
4 u |
|
The number of girls at first and in the end remains unchanged.
Number of more boys than girls at first
= 9 u - 4 u
= 5 u
5 u = 150
1 u = 150 ÷ 5 = 30
Number of boys that left
= 9 u - 1 u
= 8 u
= 8 x 30
= 240
Answer(s): 240