Tommy and Andy went shopping with a total amount of $420. They had $350 left after shopping. Tommy's remaining money was 3 times the amount he paid for. Andy's remaining money was 7 times the amount he had spent.
- How much did Andy spend?
- How much did Andy bring along for shopping?
| |
Tommy |
Andy |
Total |
| Before |
4 u |
8 p |
420 |
| Change |
- 1 u |
- 1 p |
- 70 |
| After |
3 u |
7 p |
350 |
(a)
Amount that Tommy and Andy spent
= 420 - 350
= $70
Amount that Tommy and Andy spent
= 1 u + 1 p
1 u + 1 p = 70
1 u = 70 - 1 p --- (1)
Amount that Tommy and Andy had left
= 3 u + 7 p
3 u + 7 p = 350
3 u = 350 - 7 p --- (2)
Make u the same.
(1)
x 3 3 u = 210 - 3 p --- (3)
(3) = (2)
210 - 3 p = 350 - 7 p
7 p - 3 p = 350 - 210
4 p = 140
1 p = 140 ÷ 4 = 35
Amount that Andy spent = $35
(b)
Amount that Andy brought along
= 8 p
= 8 x 35
= $280
Answer(s): (a) $35; (b) $280
