Tim decides to do a movie marathon.  The first movie is 2 hours long.  The next movie is 50% longer.  And the last movie is 1 hour shorter than the combined time of the previous 2 movies.  How long was his movie marathon?
The second movie was 2*.5=<T>multiply(2, 0.5)=1.0` hour longer than the first movie
So the second movie was 2+1=<T>add(2, 1)=3 hours long
That means the first two movies had a combined time of 3+2=<T>add(3, 2)=5 hours
So the last movie had a length of 5-1=<T>subtract(5, 1)=4 hours
That means the marathon lasted 5+4=<T>add(5, 4)=9 hours
