Hilda and Risa had $170. Risa had $42 more than Hilda. Hilda spent 4 times as much as Risa and was left with
25 as much as Risa. How much did Hilda spend more than Risa?
| |
Make p the same
(1)x5 = (3) |
Hilda
(1) |
Risa
(2) |
Make p the same
(2)x2 = (4) |
Total
|
Comparing Hilda
and Risa at first |
|
|
$42 more |
|
$170 |
| Before |
$320 |
$64 |
$106 |
$212 |
|
| Change |
- 20 u |
- 4 u |
- 1 u |
- 2 u |
|
| After |
10 p |
2 p |
5 p |
10 p |
|
Amount that Hilda had at first
= (170 - 42) ÷ 2
= 128 ÷ 2
= $64
Amount that Risa had at first
= 64 + 42
= $106
64 - 4 u = 2 p --- (1)
106 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
320 - 20 u =
10 p --- (3)
(2)
x 2
212 - 2 u =
10 p --- (4)
(4) = (3)
212 - 2 u = 320 - 20 u
20 u - 2 u = 320 - 212
18 u = 108
1 u = 108 ÷ 18 = 6
Amount that Hilda spent more than Risa
= 4 u - 1 u
= 3 u
= 3 x 6
= $18
Answer(s): $18
