piecewise problem

A man walks for 45 minutes at a rate of 3 mph, then jogs for 75 minutes at a rate of 5 mph, then sits and rests for 30 minutes, and finally walks for 1 hour and half.Find the rule of the function that expresses this distance traveled as a function of time [ Caution: Don't mix up the units of time ; use either minutes or hours , not both]

could someone help me with this problem? I sketched the graph .the ranges I got are from 0 to .75 , .75 to 2, 2 to 2.5 and 2.5 to 4 .However, I don't know how to write the rules.