Risa had an equal number of $100 and $20 notes. After spending 41 pieces of $20 and 37 pieces of $100 notes, the ratio of the $100 notes to $20 notes left was 7 : 3. Find the value of the notes left.
| |
$100 |
$20 |
| Before |
7 u + 37 |
3 u + 41 |
| Change |
- 37 |
- 41 |
| After |
7 u |
3 u |
Number of $100 notes at first = 7 u + 37
Number of $20 notes at first = 3 u + 41
The number of $100 and $20 notes at first is the same.
7 u + 37 = 3 u + 41
7 u - 3 u = 41 - 37
4 u = 4
1 u = 4 ÷ 4 = 1
Value of $100-notes left
= 7 u x 100
= 7 x 1 x 100
= $700
Value of $20-notes left
= 3 u x 20
= 3 x 1 x 20
= $60
Value of notes left
= 700 + 60
= $760
Answer(s): $760
