Adam and Bryan have a total of $170.
Adam spends
15 of his money and
Bryan spends
17 of his money.
They spend $30 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 = 170 --- (1)
Total amount that they spend = 1 u + 1 p = 30 --- (2)
(2)
x 7 7 u + 7 p = 210 --- (3)
(3) - (1)
(7 u + 7 p) - (5 u + 7 p) = 210 - 170
7 u + 7 p - 5 u - 7 p = 210 - 170
7 u - 5 u + 7 p - 7 p = 40
7 u - 5 u = 40
2 u = 40
1 u = 40 ÷ 2 = 20
Substitute 1 u = 20 into (1).
5 u + 7 p = 170
5 x 20 + 7 p = 170
100 + 7 p = 170
7 p = 170 - 100 = 70
1 p = 70 ÷ 7 = 10
Amount that Adam has at first
= 5 u
= 5 x 20
= $100
(b)
Amount that Bryan has in the end
= 7 p - 1 p
= 6 p
= 6 x 10
= $60
Answer(s): (a) $100; (b) $60