The ratio of the number of $2-notes to $20-notes in Marion's wallet was 1 : 4. Marion 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 Marion's wallet at first?
|
$2-notes |
$20-notes |
Before |
1 u |
4 u |
Change |
+ 120 |
- 12 |
After |
1 u + 120 |
4 u - 12 |
Value of 12 pieces of $20-notes
= 12 x 20
= $240
Number of $2-notes that Marion exchanged for
= 240 ÷ 2
= 120
After the exchange, Marion had an equal number of $2-notes and $20-notes.
4 u - 12 = 1 u + 120
4 u - 1 u = 120 + 12
3 u = 132
1 u = 132 ÷ 3 = 44
Number of $2-notes at first
= 1 u
= 44
Value of $2-notes at first
= 44 x 2
= $88
Number of $20-notes at first
= 4 u
= 4 x 44
= 176
Value of $20-notes at first
= 176 x 20
= $3520
Total value of $2-notes and $20-notes at first
= 88 + 3520
= $3608
Answer(s): $3608