David had $150 less than Ivan. If Ivan spends $120 and David's mother gave David $90, Ivan will have
13 as much money as David. How much money did David and Ivan have?
| |
Make p the same
(1)x3 = (3) |
David
(1) |
Ivan
(2) |
| Before |
3 u |
1 u |
1 u + 150 |
| Change |
- 360 |
- 120 |
+ 90 |
| After |
3 p |
1 p |
3 p |
Since David had $150 less than Ivan, this means Ivan had $150 more than David.
1 u - 120 = 1 p --- (1)
1 u + 150 + 90 = 3 p
1 u + 240 =
3 p --- (2)
Make p the same.
(1)
x3
3 u - 360 =
3 p --- (3)
(3) = (2)
3 u - 360 = 1 u + 240
3 u - 1 u = 240 + 360
2 u = 600
1 u = 600 ÷ 2 = 300
Total amount that David and Ivan had
= 1 u + 1 u + 150
= 2 u + 150
= 2 x 300 + 150
= 600 + 150
= $750
Answer(s): $750
