The ratio of the number of $2-notes to $20-notes in Yoko's jar was 1 : 6. Yoko exchanged 10 pieces of $20-notes for $2-notes. She then had an equal number of $2-notes and $20-notes. What was the total value of $2-notes and $20-notes in Yoko's jar at first?
| |
$2-notes |
$20-notes |
| Before |
1 u |
6 u |
| Change |
+ 100 |
- 10 |
| After |
1 u + 100 |
6 u - 10 |
Value of 10 pieces of $20-notes
= 10 x 20
= $200
Number of $2-notes that Yoko exchanged for
= 200 ÷ 2
= 100
After the exchange, Yoko had an equal number of $2-notes and $20-notes.
6 u - 10 = 1 u + 100
6 u - 1 u = 100 + 10
5 u = 110
1 u = 110 ÷ 5 = 22
Number of $2-notes at first
= 1 u
= 22
Value of $2-notes at first
= 22 x 2
= $44
Number of $20-notes at first
= 6 u
= 6 x 22
= 132
Value of $20-notes at first
= 132 x 20
= $2640
Total value of $2-notes and $20-notes at first
= 44 + 2640
= $2684
Answer(s): $2684
