Liam bought 25 pencils and Bobby bought 36 pencils. After Bobby used
25 times as many pencils as Liam, he was left with thrice as many pencils as Liam. How many pencils did each of them have in the end?
- Liam
- Bobby
| |
Make p the same.
(1)x3 = (3) |
Liam
(1) |
Bobby
(2) |
| Before |
75 |
25 |
36 |
| Change |
- 15 u |
- 5 u |
- 2 u |
| After |
3 p |
1 p |
3 p |
(a)
25 - 5 u = 1 p --- (1)
36 - 2 u =
3 p --- (2)
(1)
x3
75 - 15 u =
3 p --- (3)
(3) = (2)
36 - 2 u = 75 - 15 u
15 u - 2 u = 75 - 36
13 u = 39
1 u = 39 ÷ 13 = 3
Number of pencils that Liam had in the end
= 25 - 5 u
= 25 - 5 x 3
= 25 - 15
= 10
(b)
1 p = 10
Number of pencils that Bobby had in the end
= 3 p
= 3 x 10
= 30
Answer(s): (a) 10; (b) 30
