The number of boys in the auditorium was
310 that of the girls. There were 245 more girls than boys. After some girls had left the auditorium, the number of boys at the auditorium was thrice the number of the remaining girls. How many girls left the auditorium?
|
Girls |
Boys |
Difference |
Before |
10 u |
3 u |
7 u |
Change |
- ? |
|
|
After |
1 u |
3 u |
|
The number of boys at first and in the end remains unchanged.
Number of more girls than boys at first
= 10 u - 3 u
= 7 u
7 u = 245
1 u = 245 ÷ 7 = 35
Number of girls that left
= 10 u - 1 u
= 9 u
= 9 x 35
= 315
Answer(s): 315