A jar contained $2 and $20 notes with a total value of $638. 10 pieces of $20 were exchanged for $2 notes of similar value. In the end, the number of $2 notes was the same as the $20 notes. How many $20 notes were there at first?
|
$2 |
$20 |
Before |
1 u - 100 |
1 u + 10 |
Change |
+ 100 |
- 10 |
After |
1 u |
1 u |
Total value of $2 and $20 notes remains unchanged after the exchange of notes of similar value.
Total value of 10 pieces of $20-notes
= 10 x 20
= $200
Number of $2-notes that 10 pieces of $20-notes were exchanged for
= 200 ÷ 2
= 100
In the end |
$2 |
$20 |
Total |
Number |
1 u |
1 u |
2 u |
Value |
2 |
20 |
|
Total Value |
2 u |
20 u |
22 u |
Total value of $2 and $20 notes
= 2 u + 20 u
= 22 u
22 u = 638
1 u = 638 ÷ 22 = 29
Number of $20 notes at first
= 1 u + 10
= 29 + 10
= 39
Answer(s): 39