Risa and Erika had $150. Erika had $46 more than Risa. Risa spent 2 times as much as Erika and was left with
25 as much as Erika. How much did Risa spend?
|
Make p the same (1)x5 = (3) |
Risa (1) |
Erika (2) |
Make p the same (2)x2 = (4) |
Total
|
Comparing Risa and Erika at first |
|
|
$46 more |
|
$150 |
Before |
$260 |
$52 |
$98 |
$196 |
|
Change |
- 10 u |
- 2 u |
- 1 u |
- 2 u |
|
After |
10 p |
2 p |
5 p |
10 p |
|
Amount that Risa had at first
= (150 - 46) ÷ 2
= 104 ÷ 2
= $52
Amount that Erika had at first
= 52 + 46
= $98
52 - 2 u = 2 p --- (1)
98 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
260 - 10 u =
10 p --- (3)
(2)
x 2
196 - 2 u =
10 p --- (4)
(4) = (3)
196 - 2 u = 260 - 10 u
10 u - 2 u = 260 - 196
8 u = 64
1 u = 64 ÷ 8 = 8
Amount that Risa spent
= 2 u
= 2 x 8
= $16
Answer(s): $16