I invest $3000 at 5% interest a year. So far I have made $600 with simple interest. How many years h

I invest $3000 at 5% interest a year. So far I have made $600 with simple interest. How many years have I been investing?

Simple interest is calculated using interest * principal.

We have 5% * 3000 = $150 interest per year

We take our $600 of total interest and divide it by our interest per year to get the total years:
$600 / $150 = 4 years