David and Luis have the same amount of money. If David spends $43 a day and Luis spends $14 a day, Luis will have $319 when David uses up all his money. If David spends $10 a day and Luis spends $43 a day, how much will David have left when Luis uses up all his money?
| |
Case 1 |
Case 2 |
| |
David |
Luis |
David |
Luis |
| Before |
43 u |
14 u + $319 |
43 u |
43 u |
| Change |
- 43 u |
- 14 u |
- 10 u |
- 43 u |
| After |
0 |
$319 |
33 u |
0 |
The amounts that David and Luis have at first are the same.
43 u = 14 u + 319
43 u - 14 u = 319
29 u = 319
1 u = 319 ÷ 29 = 11
Amount that David will have left when Luis uses up all his money
= 43 u - 10 u
= 33 u
= 33 x 11
= $363
Answer(s): $363
