The ratio of the number of $10-notes to $20-notes in Pamela's handbag was 1 : 8. Pamela exchanged 7 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 Pamela's handbag at first?
|
$10-notes |
$20-notes |
Before |
1 u |
8 u |
Change |
+ 14 |
- 7 |
After |
1 u + 14 |
8 u - 7 |
Value of 7 pieces of $20-notes
= 7 x 20
= $140
Number of $10-notes that Pamela exchanged for
= 140 ÷ 10
= 14
After the exchange, Pamela had an equal number of $10-notes and $20-notes.
8 u - 7 = 1 u + 14
8 u - 1 u = 14 + 7
7 u = 21
1 u = 21 ÷ 7 = 3
Number of $10-notes at first
= 1 u
= 3
Value of $10-notes at first
= 3 x 10
= $30
Number of $20-notes at first
= 8 u
= 8 x 3
= 24
Value of $20-notes at first
= 24 x 20
= $480
Total value of $10-notes and $20-notes at first
= 30 + 480
= $510
Answer(s): $510