The ratio of the number of $2-notes to $10-notes in Sarah's wallet was 1 : 4. Sarah exchanged 15 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 wallet at first?
|
$2-notes |
$10-notes |
Before |
1 u |
4 u |
Change |
+ 75 |
- 15 |
After |
1 u + 75 |
4 u - 15 |
Value of 15 pieces of $10-notes
= 15 x 10
= $150
Number of $2-notes that Sarah exchanged for
= 150 ÷ 2
= 75
After the exchange, Sarah had an equal number of $2-notes and $10-notes.
4 u - 15 = 1 u + 75
4 u - 1 u = 75 + 15
3 u = 90
1 u = 90 ÷ 3 = 30
Number of $2-notes at first
= 1 u
= 30
Value of $2-notes at first
= 30 x 2
= $60
Number of $10-notes at first
= 4 u
= 4 x 30
= 120
Value of $10-notes at first
= 120 x 10
= $1200
Total value of $2-notes and $10-notes at first
= 60 + 1200
= $1260
Answer(s): $1260