One model for car depreciation is as follows where c is the Original cost v is the value of the car after t years and r is the rate of depreciation if the original cost of the car was 21,000dollars and the rate of depreciation is 15% what will be the value of the car after 5 years round to the nearest dollar

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.