At the concert, there were 84 less boys than girls. After
13 of the boys and
45 of the girls had left the hall, there was an equal number of boys and girls that remained behind. Find the number of boys who were present at the concert at first.
|
Boys |
Girls |
Less |
Before |
3x1 = 3 u |
5x2 = 10 u |
7 u |
Change |
- 1x1 = - 1 u |
- 4x2 = - 8 u |
|
After |
2x1 = 2 u |
1x2 = 2 u |
|
Fraction of boys that remained
= 1 -
13 =
23 Fraction of girls that remained
= 1 -
45 =
15 The number of boys and girls in the end is the same. Make the number of boys and girls in the end the same. LCM of 2 and 1 is 2.
2x13x1 Boys =
1x25x2 Girls
23 Boys =
210 Girls
Total boys at first = 3 u
Total girls at first = 10 u
Number of less boys than girls at first
= 10 u - 3 u
= 7 u
7 u = 84
1 u = 84 ÷ 7 = 12
Number of boys at first
= 3 u
= 3 x 12
= 36
Answer(s): 36