The ratio of the number of $2-notes to $10-notes in Yoko's bag was 1 : 5. Yoko exchanged 4 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 Yoko's bag at first?
|
$2-notes |
$10-notes |
Before |
1 u |
5 u |
Change |
+ 20 |
- 4 |
After |
1 u + 20 |
5 u - 4 |
Value of 4 pieces of $10-notes
= 4 x 10
= $40
Number of $2-notes that Yoko exchanged for
= 40 ÷ 2
= 20
After the exchange, Yoko had an equal number of $2-notes and $10-notes.
5 u - 4 = 1 u + 20
5 u - 1 u = 20 + 4
4 u = 24
1 u = 24 ÷ 4 = 6
Number of $2-notes at first
= 1 u
= 6
Value of $2-notes at first
= 6 x 2
= $12
Number of $10-notes at first
= 5 u
= 5 x 6
= 30
Value of $10-notes at first
= 30 x 10
= $300
Total value of $2-notes and $10-notes at first
= 12 + 300
= $312
Answer(s): $312