A jar contained $10 and $5 notes with a total value of $300. 4 pieces of $5 were exchanged for $10 notes of similar value. In the end, the number of $10 notes was the same as the $5 notes. How many $10 notes were there at first?
| |
$10 |
$5 |
| Before |
1 u - 2 |
1 u + 4 |
| Change |
+ 2 |
- 4 |
| After |
1 u |
1 u |
Total value of $10 and $5 notes remains unchanged after the exchange of notes of similar value.
Total value of 4 pieces of $5-notes
= 4 x 5
= $20
Number of $10-notes that 4 pieces of $5-notes were exchanged for
= 20 ÷ 10
= 2
| In the end |
$10 |
$5 |
Total |
| Number |
1 u |
1 u |
2 u |
| Value |
10 |
5 |
|
| Total Value |
10 u |
5 u |
15 u |
Total value of $10 and $5 notes
= 10 u + 5 u
= 15 u
15 u = 300
1 u = 300 ÷ 15 = 20
Number of $10 notes at first
= 1 u - 2
= 20 - 2
= 18
Answer(s): 18
