A jar contained $20 and $2 notes with a total value of $440. 10 pieces of $2 were exchanged for $20 notes of similar value. In the end, the number of $20 notes was the same as the $2 notes. How many $20 notes were there at first?
| |
$20 |
$2 |
| Before |
1 u - 1 |
1 u + 10 |
| Change |
+ 1 |
- 10 |
| After |
1 u |
1 u |
Total value of $20 and $2 notes remains unchanged after the exchange of notes of similar value.
Total value of 10 pieces of $2-notes
= 10 x 2
= $20
Number of $20-notes that 10 pieces of $2-notes were exchanged for
= 20 ÷ 20
= 1
| In the end |
$20 |
$2 |
Total |
| Number |
1 u |
1 u |
2 u |
| Value |
20 |
2 |
|
| Total Value |
20 u |
2 u |
22 u |
Total value of $20 and $2 notes
= 20 u + 2 u
= 22 u
22 u = 440
1 u = 440 ÷ 22 = 20
Number of $20 notes at first
= 1 u - 1
= 20 - 1
= 19
Answer(s): 19
