Answer:
[tex]\large\boxed{f^{-1}(x)=\dfrac{1}{4}x}[/tex]
Step-by-step explanation:
[tex]f(x)=4x\to y=4x\\\\\text{exchange x to y and vice versa:}\\\\x=4y\qquad\text{solve for}\ y:\\\\4y=x\qquad\text{divide both sides by 4}\\\\y=\dfrac{x}{4}=\dfrac{1}{4}x[/tex]
