Could you help me with this?

Answer this question, only if you know the answer. 30 points and brainliest!

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.

0if x and y vary inversely and y=6 as x=7, what is the constant of variation?