David bought 28 notebooks and Riordan bought 52 notebooks. After Riordan used
35 times as many notebooks as David, he was left with five times as many notebooks as David. How many notebooks did each of them have in the end?
- David
- Riordan
| |
Make p the same.
(1)x5 = (3) |
David
(1) |
Riordan
(2) |
| Before |
140 |
28 |
52 |
| Change |
- 25 u |
- 5 u |
- 3 u |
| After |
5 p |
1 p |
5 p |
(a)
28 - 5 u = 1 p --- (1)
52 - 3 u =
5 p --- (2)
(1)
x5
140 - 25 u =
5 p --- (3)
(3) = (2)
52 - 3 u = 140 - 25 u
25 u - 3 u = 140 - 52
22 u = 88
1 u = 88 ÷ 22 = 4
Number of notebooks that David had in the end
= 28 - 5 u
= 28 - 5 x 4
= 28 - 20
= 8
(b)
1 p = 8
Number of notebooks that Riordan had in the end
= 5 p
= 5 x 8
= 40
Answer(s): (a) 8; (b) 40
