A jar contained $20 and $5 notes with a total value of $550. 4 pieces of $5 were exchanged for $20 notes of similar value. In the end, the number of $20 notes was the same as the $5 notes. How many $20 notes were there at first?
| |
$20 |
$5 |
| Before |
1 u - 1 |
1 u + 4 |
| Change |
+ 1 |
- 4 |
| After |
1 u |
1 u |
Total value of $20 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 $20-notes that 4 pieces of $5-notes were exchanged for
= 20 ÷ 20
= 1
| In the end |
$20 |
$5 |
Total |
| Number |
1 u |
1 u |
2 u |
| Value |
20 |
5 |
|
| Total Value |
20 u |
5 u |
25 u |
Total value of $20 and $5 notes
= 20 u + 5 u
= 25 u
25 u = 550
1 u = 550 ÷ 25 = 22
Number of $20 notes at first
= 1 u - 1
= 22 - 1
= 21
Answer(s): 21
