On Thursday, Esther, Lucy, Tiffany and Risa spent a total of $139. On Friday, Esther spent twice of what she spent on Thursday, Lucy spent the same as what she spent on Thursday, Tiffany spent $12 less than what she spent on Thursday, and Risa spent $6 more than what she spent on Thursday. All of them spent an equal amount on Friday. How much did Esther and Risa spend altogether on Thursday?
|
Esther |
Lucy |
Tiffany |
Risa |
Total |
Before |
1 u |
2 u |
2 u + $12 |
2 u - $6 |
$139 |
Change |
x 2 |
|
- $12 |
+ $6 |
|
After |
2 u |
2 u |
2 u |
2 u |
|
Total amount that the four girls spent on Thursday
= 1 u + 2 u + 2 u + 12 + 2 u - 6
= 7 u + 12 - 6
= 7 u + 6
7 u + 6 = 139
7 u = 139 - 6
7 u = 133
1 u = 133 ÷ 7 = 19
Total amount that Esther and Risa spent on Thursday
= 1 u + 2 u - 6
= 3 u - 6
= 3 x 19 - 6
= 57 - 6
= $51
Answer(s): $51