PSLEBarbara and Mary went shopping together with a total amount of $99.60. Barbara spent 2 times as much as Mary. The amount Mary had left was $31 more than what she had spent. She had 2 times as much money left as Barbara.
(a) How much money did Mary spend?
(b) How much money did Barbara have at first?
|
Barbara |
Mary |
Total |
Before |
2.5 u + 15.5 |
2 u + 31 |
99.60 |
Change |
- 2 u |
- 1 u |
|
After |
0.5 u + 15.5 |
1 u + 31 |
|
(a)
Total amount that Barbara and Mary had at first
= (2.5 u + 15.5) + (2 u + 31)
= 2.5 u + 2 u + 15.5 + 31
= 4.5 u + 46.5
4.5 u + 46.5 = 99.6
4.5 u = 99.6 - 46.5
4.5 u = 53.1
1 u = 53.1 ÷ 4.5 = 11.8
Amount that Mary had at first
= 1 u
= $11.80
(b)
Amount that Barbara had at first
= 2.5 u + 15.5
= (2.5 x 11.8) + 15.5
= 29.5 + 15.5
= $45
Answer(s): (a) $11.80; (b) $45