The ratio of the number of $10-notes to $50-notes in Risa's purse was 1 : 4. Risa exchanged 12 pieces of $50-notes for $10-notes. She then had an equal number of $10-notes and $50-notes. What was the total value of $10-notes and $50-notes in Risa's purse at first?
|
$10-notes |
$50-notes |
Before |
1 u |
4 u |
Change |
+ 60 |
- 12 |
After |
1 u + 60 |
4 u - 12 |
Value of 12 pieces of $50-notes
= 12 x 50
= $600
Number of $10-notes that Risa exchanged for
= 600 ÷ 10
= 60
After the exchange, Risa had an equal number of $10-notes and $50-notes.
4 u - 12 = 1 u + 60
4 u - 1 u = 60 + 12
3 u = 72
1 u = 72 ÷ 3 = 24
Number of $10-notes at first
= 1 u
= 24
Value of $10-notes at first
= 24 x 10
= $240
Number of $50-notes at first
= 4 u
= 4 x 24
= 96
Value of $50-notes at first
= 96 x 50
= $4800
Total value of $10-notes and $50-notes at first
= 240 + 4800
= $5040
Answer(s): $5040