The ratio of the number of $10-notes to $20-notes in Julie's handbag was 1 : 3. Julie exchanged 8 pieces of $20-notes for $10-notes. She then had an equal number of $10-notes and $20-notes. What was the total value of $10-notes and $20-notes in Julie's handbag at first?
|
$10-notes |
$20-notes |
Before |
1 u |
3 u |
Change |
+ 16 |
- 8 |
After |
1 u + 16 |
3 u - 8 |
Value of 8 pieces of $20-notes
= 8 x 20
= $160
Number of $10-notes that Julie exchanged for
= 160 ÷ 10
= 16
After the exchange, Julie had an equal number of $10-notes and $20-notes.
3 u - 8 = 1 u + 16
3 u - 1 u = 16 + 8
2 u = 24
1 u = 24 ÷ 2 = 12
Number of $10-notes at first
= 1 u
= 12
Value of $10-notes at first
= 12 x 10
= $120
Number of $20-notes at first
= 3 u
= 3 x 12
= 36
Value of $20-notes at first
= 36 x 20
= $720
Total value of $10-notes and $20-notes at first
= 120 + 720
= $840
Answer(s): $840