Kylie had an equal number of $10 and $20 notes. After spending 48 pieces of $20 and 30 pieces of $10 notes, the ratio of the $10 notes to $20 notes left was 7 : 4. Find the value of the notes left.
| |
$10 |
$20 |
| Before |
7 u + 30 |
4 u + 48 |
| Change |
- 30 |
- 48 |
| After |
7 u |
4 u |
Number of $10 notes at first = 7 u + 30
Number of $20 notes at first = 4 u + 48
The number of $10 and $20 notes at first is the same.
7 u + 30 = 4 u + 48
7 u - 4 u = 48 - 30
3 u = 18
1 u = 18 ÷ 3 = 6
Value of $10-notes left
= 7 u x 10
= 7 x 6 x 10
= $420
Value of $20-notes left
= 4 u x 20
= 4 x 6 x 20
= $480
Value of notes left
= 420 + 480
= $900
Answer(s): $900
