Answer:
$27.25
Step-by-step explanation:
We must first determine the average balance:
(900 x 30 days) / 30 days = $900
($1,300 x 20 days) / 30 days = $866.67
($100 x 15 days) / 30 days = $50
average balance = $900 + $866.67 + $50 = $1,816.67
now we multiply times APR:
daily balance x APR/12 = $1,816.67 x (0.18/12) = $27.25