Adam and Bryan have a total of $139.
Adam spends
15 of his money and
Bryan spends
17 of his money.
They spend $21 altogether.
- How much does Adam have at first?
- How much does Bryan have in the end?
|
Adam |
Bryan |
Before |
5 u |
7 p |
Change |
- 1 u |
- 1 p |
After |
4 u |
6 p |
(a)
Amount that Adam has at first = 5 u
Amount that Bryan has at first = 7 p
Total amount that they have = 5 u + 7 p = 139 --- (1)
Total amount that they spend = 1 u + 1 p = 21 --- (2)
(2)
x 7 7 u + 7 p = 147 --- (3)
(3) - (1)
(7 u + 7 p) - (5 u + 7 p) = 147 - 139
7 u + 7 p - 5 u - 7 p = 147 - 139
7 u - 5 u + 7 p - 7 p = 8
7 u - 5 u = 8
2 u = 8
1 u = 8 ÷ 2 = 4
Substitute 1 u = 4 into (1).
5 u + 7 p = 139
5 x 4 + 7 p = 139
20 + 7 p = 139
7 p = 139 - 20 = 119
1 p = 119 ÷ 7 = 17
Amount that Adam has at first
= 5 u
= 5 x 4
= $20
(b)
Amount that Bryan has in the end
= 7 p - 1 p
= 6 p
= 6 x 17
= $102
Answer(s): (a) $20; (b) $102