On Friday, Penelope, Lucy, Gwen and Mary spent a total of $117. On Saturday, Penelope spent twice of what she spent on Friday, Lucy spent the same as what she spent on Friday, Gwen spent $18 less than what she spent on Friday, and Mary spent $6 more than what she spent on Friday. All of them spent an equal amount on Saturday. How much did Penelope and Mary spend altogether on Friday?
| |
Penelope |
Lucy |
Gwen |
Mary |
Total |
| Before |
1 u |
2 u |
2 u + $18 |
2 u - $6 |
$117 |
| Change |
x 2 |
|
- $18 |
+ $6 |
|
| After |
2 u |
2 u |
2 u |
2 u |
|
Total amount that the four girls spent on Friday
= 1 u + 2 u + 2 u + 18 + 2 u - 6
= 7 u + 18 - 6
= 7 u + 12
7 u + 12 = 117
7 u = 117 - 12
7 u = 105
1 u = 105 ÷ 7 = 15
Total amount that Penelope and Mary spent on Friday
= 1 u + 2 u - 6
= 3 u - 6
= 3 x 15 - 6
= 45 - 6
= $39
Answer(s): $39
