given the function f( x) =5 x + 2 find the value of f (3x)- 3f(x) + 4

given the function f( x) =5 x + 2 find the value of f(3x)- 3f(x) + 4 f (3x)= 5*3x)+2= 15x+2...(i), 3f(x)= 3(5x+2)= 15x+6...(ii) So f (3x)- 3f(x) + 4= 15x+2 + 15x+6+4= 30x+12