Ariane borrows $400 on a 4-year loan. she is charged 5% simple interest per year . how much interest is she charged for 4 years? what is the total amount she has to pay back?

Interests charged for 4 years: $80Total amount to pay back:$480

Step-by-step explanation:

To know the future value of an specific amount that is borrowed from a  bank we use the following equation: , where FV is future value, PV present value, n the amount of periods and i the interest rate.In this particular case, the present value of the loan is $400, n=4 (4 years), i=5%. Then the future value equals: . Then FV= $480, which is the total amount of money she would have to return in 4 years.The interest paid can be calculated as the total amount paid ($480) minus the inicial loan ($400), which means that total interests paid= FV- PV= $80.

Iknow one of the answers is a and maybe b but not 100% sure about b