The number of $10, $20 and $50 notes in a piggy bank is in the ratio of 7 : 1 : 6. The notes are worth $3900 altogether. Find the total number of $20 and $50 notes.
|
$10 |
$20 |
$50 |
Total |
Number |
7 u |
1 u |
6 u |
|
Value |
$10 |
$20 |
$50 |
|
Total value |
70 u |
20 u |
300 u |
$3900 |
Total value of $10, $20 and $50 notes
= 70 u + 20 u + 300 u
= 390 u
390 u = 3900
1 u = 3900 ÷ 390 = 10
Number of $20 and $50 notes
= 1 u + 6 u
= 7 u
= 7 x 10
= 70
Answer(s): 70