The number of $10, $20 and $50 notes in a piggy bank is in the ratio of 7 : 3 : 7. The notes are worth $4320 altogether. Find the total number of $10 and $20 notes.
| |
$10 |
$20 |
$50 |
Total |
| Number |
7 u |
3 u |
7 u |
|
| Value |
$10 |
$20 |
$50 |
|
| Total value |
70 u |
60 u |
350 u |
$4320 |
Total value of $10, $20 and $50 notes
= 70 u + 60 u + 350 u
= 480 u
480 u = 4320
1 u = 4320 ÷ 480 = 9
Number of $10 and $20 notes
= 7 u + 3 u
= 10 u
= 10 x 9
= 90
Answer(s): 90
