In a box of notes, the number of $2, $10 and $20 are in ratio of 7 : 5 : 6.
37 of the $2-notes is taken out and another 15 $10-notes are added. The remaining notes are worth $1930. Find the difference between the value of $20-notes and $2-notes in the end.
| |
$2 |
$10 |
$20 |
| Before |
7 u |
5 u |
6 u |
| Change |
- 3 u |
+ 15 |
|
| After |
4 u |
5 u + 15 |
6 u |
| |
$2 |
$10 |
$20 |
Total |
| Number |
4 u |
5 u + 15 |
6 u |
|
| Value |
2 |
10 |
20 |
|
| Total value |
8 u |
50 u + 150 |
120 u |
1930 |
Total value of the notes
= 8 u + 50 u + 150 + 120 u
= 178 u + 150
178 u + 150 = 1930
178 u = 1930 - 150
178 u = 1780
1 u = 1780 ÷ 178 = 10
Difference between the value of $20-notes and $2-notes in the end
= 120 u - 8 u
= 112 u
= 112 x 10
= $1120
Answer(s): $1120
