Lee, Bryan and Michael had a total of 36 erasers. The ratio of the number of erasers that Bryan had to the number of erasers that Michael had was 2 : 3. After Lee and Bryan each gave away half of their erasers, the 3 children had 24 erasers left. How many erasers did Bryan and Michael have at first?
| |
Lee |
Bryan |
Michael |
Total |
| Before |
2 p |
2 u |
3 u |
36 |
| Change |
- 1 p |
- 1 u |
|
- 12 |
| After |
1 p |
1 u |
3 u |
24 |
Total number of erasers that Lee and Bryan gave away
= 36 - 24
= 12
1 p + 1 u = 12 --- (1)
1 p + 1 u + 3 u = 24
1 p + 4 u = 24 --- (2)
(2) - (1)
(1 p + 4 u) - (1 p + 1 u) = 24 - 12
4 u - 1 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Total number of erasers that Bryan and Michael had at first
= 2 u + 3 u
= 5 u
= 5 x 4
= 20
Answer(s): 20
