The ratio of the number of $10-notes to $20-notes in Tina's handbag was 1 : 4. Tina exchanged 6 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 Tina's handbag at first?
|
$10-notes |
$20-notes |
Before |
1 u |
4 u |
Change |
+ 12 |
- 6 |
After |
1 u + 12 |
4 u - 6 |
Value of 6 pieces of $20-notes
= 6 x 20
= $120
Number of $10-notes that Tina exchanged for
= 120 ÷ 10
= 12
After the exchange, Tina had an equal number of $10-notes and $20-notes.
4 u - 6 = 1 u + 12
4 u - 1 u = 12 + 6
3 u = 18
1 u = 18 ÷ 3 = 6
Number of $10-notes at first
= 1 u
= 6
Value of $10-notes at first
= 6 x 10
= $60
Number of $20-notes at first
= 4 u
= 4 x 6
= 24
Value of $20-notes at first
= 24 x 20
= $480
Total value of $10-notes and $20-notes at first
= 60 + 480
= $540
Answer(s): $540