Mary had an equal number of $50 and $5 notes. After spending 21 pieces of $5 and 15 pieces of $50 notes, the ratio of the $50 notes to $5 notes left was 7 : 4. Find the value of the notes left.
| |
$50 |
$5 |
| Before |
7 u + 15 |
4 u + 21 |
| Change |
- 15 |
- 21 |
| After |
7 u |
4 u |
Number of $50 notes at first = 7 u + 15
Number of $5 notes at first = 4 u + 21
The number of $50 and $5 notes at first is the same.
7 u + 15 = 4 u + 21
7 u - 4 u = 21 - 15
3 u = 6
1 u = 6 ÷ 3 = 2
Value of $50-notes left
= 7 u x 50
= 7 x 2 x 50
= $700
Value of $5-notes left
= 4 u x 5
= 4 x 2 x 5
= $40
Value of notes left
= 700 + 40
= $740
Answer(s): $740
