The ratio of the number of $2-notes to $20-notes in Hazel's jar was 1 : 7. Hazel exchanged 12 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 Hazel's jar at first?
| |
$2-notes |
$20-notes |
| Before |
1 u |
7 u |
| Change |
+ 120 |
- 12 |
| After |
1 u + 120 |
7 u - 12 |
Value of 12 pieces of $20-notes
= 12 x 20
= $240
Number of $2-notes that Hazel exchanged for
= 240 ÷ 2
= 120
After the exchange, Hazel had an equal number of $2-notes and $20-notes.
7 u - 12 = 1 u + 120
7 u - 1 u = 120 + 12
6 u = 132
1 u = 132 ÷ 6 = 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
= 7 u
= 7 x 22
= 154
Value of $20-notes at first
= 154 x 20
= $3080
Total value of $2-notes and $20-notes at first
= 44 + 3080
= $3124
Answer(s): $3124
