Answer:
its gonna be -4
Step-by-step explanation:
First find the amount of each payment:

The total cost will be 40 payments plus service charges.

The percentage is the service charge divided by total cost:
25%
Divide 12 by 3 and you'll get 4.
That means 1/4 or a quarter of the 12 is 3.
(Convert the fraction to its percentage form)
1/4 or 1 divided by 4 equals 0.25
Multiply 0.25 by 100 and you'll get 25%
The answer is =324°*(\pi )/(180<span>°</span>)