Jack, Luke and John had 72 pencils. After Jack used 11 pencils and Luke used
47 of her pencils, Jack had twice as many pencils left as Luke. John bought another 14 pencils, he had four times the number of pencils Luke had left. How many pencils did John have at first?
| |
Jack |
Luke |
John |
Total |
| Before |
6 u + 11 |
7 u |
12 u - 14 |
72 |
| Change |
- 11 |
- 4 u |
+ 14 |
|
| After |
6 u |
3 u |
12 u |
|
Comparing Jack
and Luke in the end |
2 |
1 |
|
|
Comparing John
and Luke in the end |
|
1 |
4 |
|
Number of pencils that Jack had in the end
= 2 x 3 u
= 6 u
Number of pencils that John had in the end
= 4 x 3 u
= 12 u
Total number of pencils at first
= 6 u + 11 + 7 u + 12 u - 14
= 25 u - 3
25 u - 3 = 72
25 u = 72 + 3
25 u = 75
1 u = 75 ÷ 25 = 3
Number of pencils that John had at first
= 12 u - 14
= 12 x 3 - 14
= 36 - 14
= 22
Answer(s): 22
