Andy, Charlie and Henry had a total of 36 erasers. The ratio of the number of erasers that Charlie had to the number of erasers that Henry had was 6 : 7. After Andy and Charlie each gave away half of their erasers, the 3 children had 25 erasers left. How many erasers did Charlie and Henry have at first?
| |
Andy |
Charlie |
Henry |
Total |
| Before |
2 p |
6 u |
7 u |
36 |
| Change |
- 1 p |
- 3 u |
|
- 11 |
| After |
1 p |
3 u |
7 u |
25 |
Total number of erasers that Andy and Charlie gave away
= 36 - 25
= 11
1 p + 3 u = 11 --- (1)
1 p + 3 u + 7 u = 25
1 p + 10 u = 25 --- (2)
(2) - (1)
(1 p + 10 u) - (1 p + 3 u) = 25 - 11
10 u - 3 u = 14
7 u = 14
1 u = 14 ÷ 7 = 2
Total number of erasers that Charlie and Henry had at first
= 6 u + 7 u
= 13 u
= 13 x 2
= 26
Answer(s): 26
