John and Billy were given some allowances each. If John spent $30 each day and Billy spent $90 each day, John would still have $2714 left when Billy spent all his allowance. If John spent $90 each day and Billy spent $30 each day, John would still have $74 left when Billy spent all his allowance.
- How much allowance did John receive?
- How much allowance did Billy receive?
|
Case 1 |
Case 2 |
|
John |
Billy |
John |
Billy |
Before |
1 u + 2714 |
3 u |
3 p + 74 |
1 p |
Change |
- 1 u |
- 3 u |
- 3 p |
- 1 p |
After |
2714 |
0 |
74 |
0 |
(a)
Simplify the ratio.
30 : 90 = 1 : 3
The allowance that Billy had at first is the same for Case 1 and Case 2.
1 p = 3 u
3 p = 9 u
The allowance that John had at first is the same for Case 1 and Case 2.
9 u + 74 = 1 u + 2714
9 u - 1 u = 2714 - 74
8 u = 2640
1 u = 2640 ÷ 8 = 330
Allowance that John received
= 1 u + 2714
= 330 + 2714
= $3044
(b)
Allowance that Billy received
= 3 u
= 3 x 330
= $990
Answers: (a) $3044; (b) $990