Please answer need for geometry

Quick translate "x is 12 units from 20" into an equation. what are the values of x being described? if you can answer any of my other questions that'd be great too

2y= 3 2 x−2 y = − 1 3 x + 1 y=− 3 1 x+1

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)