John attends a protest for 4 days.  He then attends a second protest for 25% longer than the first.  How many days did he spend protesting?
The second protest was 4*.25=<T>multiply(4, 0.25)=1.0 day longer than the first.
So the second protest was 4+1=<T>add(4, 1)=5 days.
Thus he spent 4+5=<T>add(4, 5)=9 days protesting.
