Answer:
Interest can be ordinary or exact. Exact interest is calculated for a 365-days period. Let's calculate how much is that. For a 365-day period amount is loan multiplied by interest rate:
A = L • I
A = 5000 • 9/100
A = $450
We already stated that this is for a 365-day period. Now let's find how much is that for a 90-day period given in this text. For this we can use the proportion:
90 : x = 365 : $450
x = 450 • 90 / 365
x = $111
