A jar contained $10 and $20 notes with a total value of $1080. 5 pieces of $20 were exchanged for $10 notes of similar value. In the end, the number of $10 notes was the same as the $20 notes. How many $20 notes were there at first?
| |
$10 |
$20 |
| Before |
1 u - 10 |
1 u + 5 |
| Change |
+ 10 |
- 5 |
| After |
1 u |
1 u |
Total value of $10 and $20 notes remains unchanged after the exchange of notes of similar value.
Total value of 5 pieces of $20-notes
= 5 x 20
= $100
Number of $10-notes that 5 pieces of $20-notes were exchanged for
= 100 ÷ 10
= 10
| In the end |
$10 |
$20 |
Total |
| Number |
1 u |
1 u |
2 u |
| Value |
10 |
20 |
|
| Total Value |
10 u |
20 u |
30 u |
Total value of $10 and $20 notes
= 10 u + 20 u
= 30 u
30 u = 1080
1 u = 1080 ÷ 30 = 36
Number of $20 notes at first
= 1 u + 5
= 36 + 5
= 41
Answer(s): 41
