Simon and Billy had $780. Simon spent
59 of his money on a home theater system. Billy spent
13 of his money on a notebook. The home theater system cost $100 more than the notebook. How much money did Simon have at first?
|
Simon |
Billy |
Total |
Before |
9 u |
+ 180 |
3x5 = 15 u |
780 |
Change |
- 5 u |
- 100 |
- 1x5 = - 5 u |
|
Comparing the home theater system and the notebook |
100 more |
|
|
After |
4 u |
+ 80 |
2x5 = 10 u |
|
100 ÷ 5 = 20
4 x 20 = 80
9 x 20 = 180
Total amount that Simon and Billy had at first
= 9 u + 180 + 15 u
= 24 u + 180
24 u + 180 = 780
24 u = 780 - 180
24 u = 600
1 u = 600 ÷ 24 = 25
Amount that Simon had at first
= 9 u + 180
= 9 x 25 + 180
= 225 + 180
= $405
Answer(s): $405