Esther and Lucy had $51 at first. Esther spent
57 of her money and Lucy spent
78 of her money. Given that they had $57 left, how much did Esther have at first?
| |
Esther |
Lucy |
Total |
| Before |
7 u |
8 p |
$51 |
| Change |
- 5 u |
- 7 p |
|
| After |
2 u |
1 p |
$57 |
7 u + 8 p = 51 --- (1)
2 u + 1 p = 57 --- (2)
(2) x 8 16 u + 8 p = 456 --- (3)
(3) - (1)
16 u - 7 u = 456 - 51
9 u = 405
1 u = 405 ÷ 9 = 45
Amount that Esther had at first
= 7 u
= 7 x 45
= $315
Answer(s): $315
