Zara and Betty had $189. Betty had $9 more than Zara. Zara spent 4 times as much as Betty and was left with
35 as much as Betty. How much did Zara spend?
| |
Make p the same
(1)x5 = (3) |
Zara
(1) |
Betty
(2) |
Make p the same
(2)x3 = (4) |
Total
|
Comparing Zara
and Betty at first |
|
|
$9 more |
|
$189 |
| Before |
$450 |
$90 |
$99 |
$297 |
|
| Change |
- 20 u |
- 4 u |
- 1 u |
- 3 u |
|
| After |
15 p |
3 p |
5 p |
15 p |
|
Amount that Zara had at first
= (189 - 9) ÷ 2
= 180 ÷ 2
= $90
Amount that Betty had at first
= 90 + 9
= $99
90 - 4 u = 3 p --- (1)
99 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
450 - 20 u =
15 p --- (3)
(2)
x 3
297 - 3 u =
15 p --- (4)
(4) = (3)
297 - 3 u = 450 - 20 u
20 u - 3 u = 450 - 297
17 u = 153
1 u = 153 ÷ 17 = 9
Amount that Zara spent
= 4 u
= 4 x 9
= $36
Answer(s): $36
