Mary and Tina had $134. Tina had $30 more than Mary. Mary spent 2 times as much as Tina and was left with
25 as much as Tina. How much did Mary spend?
| |
Make p the same
(1)x5 = (3) |
Mary
(1) |
Tina
(2) |
Make p the same
(2)x2 = (4) |
Total
|
Comparing Mary
and Tina at first |
|
|
$30 more |
|
$134 |
| Before |
$260 |
$52 |
$82 |
$164 |
|
| Change |
- 10 u |
- 2 u |
- 1 u |
- 2 u |
|
| After |
10 p |
2 p |
5 p |
10 p |
|
Amount that Mary had at first
= (134 - 30) ÷ 2
= 104 ÷ 2
= $52
Amount that Tina had at first
= 52 + 30
= $82
52 - 2 u = 2 p --- (1)
82 - 1 u = 5 p --- (2)
Make p the same.
(1)
x 5
260 - 10 u =
10 p --- (3)
(2)
x 2
164 - 2 u =
10 p --- (4)
(4) = (3)
164 - 2 u = 260 - 10 u
10 u - 2 u = 260 - 164
8 u = 96
1 u = 96 ÷ 8 = 12
Amount that Mary spent
= 2 u
= 2 x 12
= $24
Answer(s): $24
