Help plz ​

What is f(3) for the quadratic function f(x)= 2x^2+ + x - 12

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.

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?