The amount of days in between payments is known as what?

In the coordinate plan (-6,9) b (3,9) c (3,3) def is shown in the coordinate plan below

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.

What are the coordinates of the point that is 1/3 of the way from a to b? a (2,-3) b (2,6)