Max borrowed $3,200.00 from his uncle at an interest rate of 1.8% for 3 years. How much interest will Max have to pay his uncle over the three year period and how much will he pay back in total?

There are two basic forms of interest - simple interest and compound interest.  

For simple interest the formula is:

I = PRT (interest equals principal, interest rate and time)

The principal is the actual amount of money you borrow or put into a savings account.