A jar contained $20 and $50 notes with a total value of $2800. 10 pieces of $50 were exchanged for $20 notes of similar value. In the end, the number of $20 notes was the same as the $50 notes. How many $20 notes were there at first?
| |
$20 |
$50 |
| Before |
1 u - 25 |
1 u + 10 |
| Change |
+ 25 |
- 10 |
| After |
1 u |
1 u |
Total value of $20 and $50 notes remains unchanged after the exchange of notes of similar value.
Total value of 10 pieces of $50-notes
= 10 x 50
= $500
Number of $20-notes that 10 pieces of $50-notes were exchanged for
= 500 ÷ 20
= 25
| In the end |
$20 |
$50 |
Total |
| Number |
1 u |
1 u |
2 u |
| Value |
20 |
50 |
|
| Total Value |
20 u |
50 u |
70 u |
Total value of $20 and $50 notes
= 20 u + 50 u
= 70 u
70 u = 2800
1 u = 2800 ÷ 70 = 40
Number of $20 notes at first
= 1 u - 25
= 40 - 25
= 15
Answer(s): 15
