You can use a plot diagram to plot the points and if they all go straight through the origin then it is proportional :)
Easy, just divide
kelly=440mi/8hr=220mi/4hr=110mi/2hr=55mi/1hr
alberto=468mi/9hr=156mi/3hr=52mi/1hr
55>52
kelly drove 55mi in 1 hour
55-52=3
she drove 3 miles more in 1 hour