The number of $10, $20 and $100 notes in a piggy bank is in the ratio of 1 : 5 : 4. The notes are worth $6120 altogether. Find the total number of $10 and $20 notes.
|
$10 |
$20 |
$100 |
Total |
Number |
1 u |
5 u |
4 u |
|
Value |
$10 |
$20 |
$100 |
|
Total value |
10 u |
100 u |
400 u |
$6120 |
Total value of $10, $20 and $100 notes
= 10 u + 100 u + 400 u
= 510 u
510 u = 6120
1 u = 6120 ÷ 510 = 12
Number of $10 and $20 notes
= 1 u + 5 u
= 6 u
= 6 x 12
= 72
Answer(s): 72