Bryan and Adam have a total of $61.
Bryan spends
13 of his money and
Adam spends
17 of his money.
They spend $11 altogether.
- How much does Bryan have at first?
- How much does Adam have in the end?
|
Bryan |
Adam |
Before |
3 u |
7 p |
Change |
- 1 u |
- 1 p |
After |
2 u |
6 p |
(a)
Amount that Bryan has at first = 3 u
Amount that Adam has at first = 7 p
Total amount that they have = 3 u + 7 p = 61 --- (1)
Total amount that they spend = 1 u + 1 p = 11 --- (2)
(2)
x 7 7 u + 7 p = 77 --- (3)
(3) - (1)
(7 u + 7 p) - (3 u + 7 p) = 77 - 61
7 u + 7 p - 3 u - 7 p = 77 - 61
7 u - 3 u + 7 p - 7 p = 16
7 u - 3 u = 16
4 u = 16
1 u = 16 ÷ 4 = 4
Substitute 1 u = 4 into (1).
3 u + 7 p = 61
3 x 4 + 7 p = 61
12 + 7 p = 61
7 p = 61 - 12 = 49
1 p = 49 ÷ 7 = 7
Amount that Bryan has at first
= 3 u
= 3 x 4
= $12
(b)
Amount that Adam has in the end
= 7 p - 1 p
= 6 p
= 6 x 7
= $42
Answer(s): (a) $12; (b) $42