# question about math?

pls help

Stacie Howard purchased a water softener for $450. She made a down payment of $50 and paid the balance off in 36 monthly payments. Find the monthly payment if the finance charge was 9% of the amount financed. Round the answer to the nearest cent.

### 1 Answer

- llafferLv 79 months agoFavourite answer
Presuming monthly interest, this is the loan payment equation:

P = r(PV) / [1 - (1 + r)^(-n)]

Where:

P = monthly payment

PV = Present Value (or principal)

r = rate per period

n = number of periods

If 9% is the annual rate, then the rate per period is 9/12 % or 0.75 % (or 0.0075)

There are 36 periods.

The PV is $400.

If we substitute this info into what we have, here's what is left:

P = 0.0075(400) / [1 - (1 + 0.0075)^(-36)]

I'll continue to use decimal approximations rounded to 7-8 digits but will attempt to keep the number as-is in the calculator to reduce errors due to rounding. Simplifying this we get:

P = 0.0075(400) / [1 - (1.0075)^(-36)]

P = 3 / (1 - 0.764149)

P = 3 / 0.2358510

P = $12.72 (rounded to the nearest penny)

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