The ratio of the number of $2-notes to $5-notes in Abi's purse was 1 : 8. Abi exchanged 8 pieces of $5-notes for $2-notes. She then had an equal number of $2-notes and $5-notes. What was the total value of $2-notes and $5-notes in Abi's purse at first?
| |
$2-notes |
$5-notes |
| Before |
1 u |
8 u |
| Change |
+ 20 |
- 8 |
| After |
1 u + 20 |
8 u - 8 |
Value of 8 pieces of $5-notes
= 8 x 5
= $40
Number of $2-notes that Abi exchanged for
= 40 ÷ 2
= 20
After the exchange, Abi had an equal number of $2-notes and $5-notes.
8 u - 8 = 1 u + 20
8 u - 1 u = 20 + 8
7 u = 28
1 u = 28 ÷ 7 = 4
Number of $2-notes at first
= 1 u
= 4
Value of $2-notes at first
= 4 x 2
= $8
Number of $5-notes at first
= 8 u
= 8 x 4
= 32
Value of $5-notes at first
= 32 x 5
= $160
Total value of $2-notes and $5-notes at first
= 8 + 160
= $168
Answer(s): $168
