Help, help, help I can’t get these

[tex]\bf f(x) = -\cfrac{1}{4}x+3\qquad \qquad \stackrel{f(x)}{x}= -\cfrac{1}{4}x+3\implies x = -\cfrac{x}{4}+3\implies x-3=\cfrac{-x}{4} \\\\\\ 4x-12=-x\implies 5x-12=0\implies 5x = 12\implies \boxed{x = \cfrac{12}{5}}[/tex]