A jar contained $5 and $10 notes with a total value of $420. 7 pieces of $10 were exchanged for $5 notes of similar value. In the end, the number of $5 notes was the same as the $10 notes. How many $10 notes were there at first?
|
$5 |
$10 |
Before |
1 u - 14 |
1 u + 7 |
Change |
+ 14 |
- 7 |
After |
1 u |
1 u |
Total value of $5 and $10 notes remains unchanged after the exchange of notes of similar value.
Total value of 7 pieces of $10-notes
= 7 x 10
= $70
Number of $5-notes that 7 pieces of $10-notes were exchanged for
= 70 ÷ 5
= 14
In the end |
$5 |
$10 |
Total |
Number |
1 u |
1 u |
2 u |
Value |
5 |
10 |
|
Total Value |
5 u |
10 u |
15 u |
Total value of $5 and $10 notes
= 5 u + 10 u
= 15 u
15 u = 420
1 u = 420 ÷ 15 = 28
Number of $10 notes at first
= 1 u + 7
= 28 + 7
= 35
Answer(s): 35