Consider the function represented by 9x + 3y = 12 with x as the independent variable. how can this function be written using function notation

Question: Consider the function represented by 9x + 3y = 12 with x as the independent variable. How can this function be written using function notation.  This function can be written using the following function notation: f(x)=__ x + 4 ; f(x)= -3x+4

9x + 3y = 12
3y = - 9x + 12
y = -9/3 x + 12/3
y = -3 x + 4

y = f(x)

Thus, f(x) = - 3x + 4