Mary and Fiona had $148. Fiona had $10 more than Mary. Mary spent 3 times as much as Fiona and was left with
35 as much as Fiona. How much did Mary spend more than Fiona?
| |
Make p the same
(1)x5 = (3) |
Mary
(1) |
Fiona
(2) |
Make p the same
(2)x3 = (4) |
Total
|
Comparing Mary
and Fiona at first |
|
|
$10 more |
|
$148 |
| Before |
$345 |
$69 |
$79 |
$237 |
|
| Change |
- 15 u |
- 3 u |
- 1 u |
- 3 u |
|
| After |
15 p |
3 p |
5 p |
15 p |
|
Amount that Mary had at first
= (148 - 10) ÷ 2
= 138 ÷ 2
= $69
Amount that Fiona had at first
= 69 + 10
= $79
69 - 3 u = 3 p --- (1)
79 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
345 - 15 u =
15 p --- (3)
(2)
x 3
237 - 3 u =
15 p --- (4)
(4) = (3)
237 - 3 u = 345 - 15 u
15 u - 3 u = 345 - 237
12 u = 108
1 u = 108 ÷ 12 = 9
Amount that Mary spent more than Fiona
= 3 u - 1 u
= 2 u
= 2 x 9
= $18
Answer(s): $18
