The ratio of the number of $10-notes to $20-notes in Olivia's handbag was 1 : 7. Olivia 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 Olivia's handbag at first?
|
$10-notes |
$20-notes |
Before |
1 u |
7 u |
Change |
+ 16 |
- 8 |
After |
1 u + 16 |
7 u - 8 |
Value of 8 pieces of $20-notes
= 8 x 20
= $160
Number of $10-notes that Olivia exchanged for
= 160 ÷ 10
= 16
After the exchange, Olivia had an equal number of $10-notes and $20-notes.
7 u - 8 = 1 u + 16
7 u - 1 u = 16 + 8
6 u = 24
1 u = 24 ÷ 6 = 4
Number of $10-notes at first
= 1 u
= 4
Value of $10-notes at first
= 4 x 10
= $40
Number of $20-notes at first
= 7 u
= 7 x 4
= 28
Value of $20-notes at first
= 28 x 20
= $560
Total value of $10-notes and $20-notes at first
= 40 + 560
= $600
Answer(s): $600