The ratio of the number of $10-notes to $20-notes in Min's purse was 1 : 4. Min exchanged 11 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 Min's purse at first?
| |
$10-notes |
$20-notes |
| Before |
1 u |
4 u |
| Change |
+ 22 |
- 11 |
| After |
1 u + 22 |
4 u - 11 |
Value of 11 pieces of $20-notes
= 11 x 20
= $220
Number of $10-notes that Min exchanged for
= 220 ÷ 10
= 22
After the exchange, Min had an equal number of $10-notes and $20-notes.
4 u - 11 = 1 u + 22
4 u - 1 u = 22 + 11
3 u = 33
1 u = 33 ÷ 3 = 11
Number of $10-notes at first
= 1 u
= 11
Value of $10-notes at first
= 11 x 10
= $110
Number of $20-notes at first
= 4 u
= 4 x 11
= 44
Value of $20-notes at first
= 44 x 20
= $880
Total value of $10-notes and $20-notes at first
= 110 + 880
= $990
Answer(s): $990
