I need help please and thank you!

A=(3B-C)D
C= 3BD-A/D

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.

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Ineed i been stuck on this question since yesterday