Help! Please Can you tell me how you do this? Thank you!

What’s the domain of this function? fastttt

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.

The cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?