make x the subject of the formula

Question

y=2x+3
x-4
hence determine the inverse of f(x) for the equation where x is not equal to 4

Answer 1

I presume you mean
y = (2x+3)/(x-4)

In that case,

xy-4y = 2x+3
x(y-2) = 4y+3
x = (4y+3)/(y-2)

so, f^-1(x) = (4x+3)/(x-2)