Sabrina and Risa had $135. Risa had $17 more than Sabrina. Sabrina spent 3 times as much as Risa and was left with
25 as much as Risa. How much did Risa spend less than Sabrina?
| |
Make p the same
(1) x 5 = (3) |
Sabrina
(1) |
Risa
(2) |
Make p the same
(2) x 2 = (4) |
Total
|
Comparing Sabrina
and Risa at first |
|
|
$17 more |
|
$135 |
| Before |
$295 |
$59 |
$76 |
$152 |
|
| Change |
- 15 u |
- 3 u |
- 1 u |
- 2 u |
|
| After |
10 p |
2 p |
5 p |
10 p |
|
Amount that Sabrina had at first
= (135 - 17) ÷ 2
= 118 ÷ 2
= $59
Amount that Risa had at first
= 59 + 17
= $76
59 - 3 u = 2 p --- (1)
76 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
295 - 15 u =
10 p --- (3)
(2)
x 2
152 - 2 u =
10 p --- (4)
(4) = (3)
152 - 2 u = 295 - 15 u
15 u - 2 u = 295 - 152
13 u = 143
1 u = 143 ÷ 13 = 11
Amount that Risa spent less than Sabrina
= 3 u - 1 u
= 2 u
= 2 x 11
= $22
Answer(s): $22
