Fiona had an equal number of $20 and $100 notes. After spending 47 pieces of $100 and 31 pieces of $20 notes, the ratio of the $20 notes to $100 notes left was 3 : 1. Find the value of the notes left.
| |
$20 |
$100 |
| Before |
3 u + 31 |
1 u + 47 |
| Change |
- 31 |
- 47 |
| After |
3 u |
1 u |
Number of $20 notes at first = 3 u + 31
Number of $100 notes at first = 1 u + 47
The number of $20 and $100 notes at first is the same.
3 u + 31 = 1 u + 47
3 u - 1 u = 47 - 31
2 u = 16
1 u = 16 ÷ 2 = 8
Value of $20-notes left
= 3 u x 20
= 3 x 8 x 20
= $480
Value of $100-notes left
= 1 u x 100
= 1 x 8 x 100
= $800
Value of notes left
= 480 + 800
= $1280
Answer(s): $1280
