Suppose you deposit $150 in a savings account that earns simple interest at a rate of 5.5% per year. how much interest will you earn after 4 years?

With simple interest, you only earn  5.5%  of the original  $150  each year.

So after  4  years, your money will earn  (5.5% x 4) =  22%  of the original $150 .

                      22% of $150

                 =  0.22  x  $150

                 =     $33 .