Bob drove for one and a half hours at 60/mph.  He then hit construction and drove for 2 hours at 45/mph. How many miles did Bob travel in those 3 and a half hours?
Bob drove for 1.5 hour * 60/mph = <T>multiply(1.5, 60)=90.0 miles.
Bod drove for 2 hour * 45/mph = <T>multiply(2, 45)=90 miles.
In total Bob drove 90 + 90 miles = <T>add(90, 90)=180 miles.
