Determine the average rate of change in braking distance, in ft/mph, between one can traveling at 50 mph and one traveling at 70 mph. Explain what this rate of change means as it relates to braking distance.

Jabari is power washing houses for a summer job. for every job, he charges an initial fee plus $30 for each hour of work. his total fee for a 4 -hour job, for instance, is $170 . jabari's total fee, f, for a single job is a function of the number, t, of hours it takes him to complete the job. write the function's formula.