Jack, Cody and Perry had a total of 139 stamps. The ratio of the number of stamps that Cody had to the number of stamps that Perry had was 4 : 7. After Jack and Cody each gave away half of their stamps, the 3 children had 108 stamps left. How many stamps did Cody and Perry have at first?
| |
Jack |
Cody |
Perry |
Total |
| Before |
2 p |
4 u |
7 u |
139 |
| Change |
- 1 p |
- 2 u |
|
- 31 |
| After |
1 p |
2 u |
7 u |
108 |
Total number of stamps that Jack and Cody gave away
= 139 - 108
= 31
1 p + 2 u = 31 --- (1)
1 p + 2 u + 7 u = 108
1 p + 9 u = 108 --- (2)
(2) - (1)
(1 p + 9 u) - (1 p + 2 u) = 108 - 31
9 u - 2 u = 77
7 u = 77
1 u = 77 ÷ 7 = 11
Total number of stamps that Cody and Perry had at first
= 4 u + 7 u
= 11 u
= 11 x 11
= 121
Answer(s): 121
