Risa had an equal number of $20 and $2 notes. After spending 46 pieces of $2 and 40 pieces of $20 notes, the ratio of the $20 notes to $2 notes left was 7 : 1. Find the value of the notes left.
| |
$20 |
$2 |
| Before |
7 u + 40 |
1 u + 46 |
| Change |
- 40 |
- 46 |
| After |
7 u |
1 u |
Number of $20 notes at first = 7 u + 40
Number of $2 notes at first = 1 u + 46
The number of $20 and $2 notes at first is the same.
7 u + 40 = 1 u + 46
7 u - 1 u = 46 - 40
6 u = 6
1 u = 6 ÷ 6 = 1
Value of $20-notes left
= 7 u x 20
= 7 x 1 x 20
= $140
Value of $2-notes left
= 1 u x 2
= 1 x 1 x 2
= $2
Value of notes left
= 140 + 2
= $142
Answer(s): $142
