The ratio of the number of $2-notes to $10-notes in Sarah's purse was 1 : 4. Sarah exchanged 12 pieces of $10-notes for $2-notes. She then had an equal number of $2-notes and $10-notes. What was the total value of $2-notes and $10-notes in Sarah's purse at first?
|
$2-notes |
$10-notes |
Before |
1 u |
4 u |
Change |
+ 60 |
- 12 |
After |
1 u + 60 |
4 u - 12 |
Value of 12 pieces of $10-notes
= 12 x 10
= $120
Number of $2-notes that Sarah exchanged for
= 120 ÷ 2
= 60
After the exchange, Sarah had an equal number of $2-notes and $10-notes.
4 u - 12 = 1 u + 60
4 u - 1 u = 60 + 12
3 u = 72
1 u = 72 ÷ 3 = 24
Number of $2-notes at first
= 1 u
= 24
Value of $2-notes at first
= 24 x 2
= $48
Number of $10-notes at first
= 4 u
= 4 x 24
= 96
Value of $10-notes at first
= 96 x 10
= $960
Total value of $2-notes and $10-notes at first
= 48 + 960
= $1008
Answer(s): $1008