Shelbie, assuming that the 5% is of the $36, then let's do it this way.
First, let's say I have a shirt that is $5 plus 8% tax. I can multiply 5 x .08 and get 40 cents, then add the 40 cents to my $5 and get $5.40.
So, we have 5% of $36. The word "of" always means to multiply. So, 36 x .05 = 1.8
For each month, Glenn paid $37.80. For four months, Glenn paid $37.80 x 4 = $151.20
Hope this helps!