Sarah had an equal number of $20 and $1 notes. After spending 28 pieces of $1 and 10 pieces of $20 notes, the ratio of the $20 notes to $1 notes left was 7 : 5. Find the value of the notes left.
| |
$20 |
$1 |
| Before |
7 u + 10 |
5 u + 28 |
| Change |
- 10 |
- 28 |
| After |
7 u |
5 u |
Number of $20 notes at first = 7 u + 10
Number of $1 notes at first = 5 u + 28
The number of $20 and $1 notes at first is the same.
7 u + 10 = 5 u + 28
7 u - 5 u = 28 - 10
2 u = 18
1 u = 18 ÷ 2 = 9
Value of $20-notes left
= 7 u x 20
= 7 x 9 x 20
= $1260
Value of $1-notes left
= 5 u x 1
= 5 x 9 x 1
= $45
Value of notes left
= 1260 + 45
= $1305
Answer(s): $1305
