To find your answer you would divide 21 by 3 which would be 7, once you've got 7 you would multiply it by 9 which would give you the amount of old houses that there is which would be 63.
Answer:
Assuming 1/20 is a 5% late fee:
$21.211
Step-by-step explanation:
67.82 x 1/20 = 3.391
67.82 + 3.391 = 71.211
3/5 + 7/10 / 7/12 - 3/10
13/10 / (35/60 - 18/60=)17/60
10/13 x 60/17 = 78/17 = 4 10/17
