Lucy had an equal number of $1 and $50 notes. After spending 42 pieces of $50 and 12 pieces of $1 notes, the ratio of the $1 notes to $50 notes left was 7 : 2. Find the value of the notes left.
| |
$1 |
$50 |
| Before |
7 u + 12 |
2 u + 42 |
| Change |
- 12 |
- 42 |
| After |
7 u |
2 u |
Number of $1 notes at first = 7 u + 12
Number of $50 notes at first = 2 u + 42
The number of $1 and $50 notes at first is the same.
7 u + 12 = 2 u + 42
7 u - 2 u = 42 - 12
5 u = 30
1 u = 30 ÷ 5 = 6
Value of $1-notes left
= 7 u x 1
= 7 x 6 x 1
= $42
Value of $50-notes left
= 2 u x 50
= 2 x 6 x 50
= $600
Value of notes left
= 42 + 600
= $642
Answer(s): $642
