Final answer:
Without the specifics for part b, such as the monthly payment or principal amount, it is impossible to precisely calculate the total amount of monthly payments over four years.
Step-by-step explanation:
The question provided does not include sufficient details for part a and part c, so we will focus on part b, which seems to refer to a financial problem involving monthly payments over a certain time period. Unfortunately, the details for part b are also missing, making it impossible to calculate the total monthly payments over four years without additional information such as the monthly payment amount or the principal amount of a loan.
Generally, if we have the monthly payment amount, we can calculate the total payment over four years by multiplying the monthly payment by the number of months in four years (48 months). For instance, if the monthly payment were $100, the total amount of monthly payments over four years would be calculated as $100 × 48 = $4,800. But, without the specifics for part b, a precise answer cannot be given.