If f : R → R defined by $f(x) =\frac{6x+3}{2}$ is an invertible function, then find ${ f }^{ -1 }$

$\frac{2x-3}{6}$ $\frac{2x-3}{3}$ $\frac{2x+3}{6}$ $\frac{2x-3}{-3}$

$\frac{2x-3}{6}$

$y=\frac{6x+3}{2}⇒2y=6x+3⇒2y-3=6x$ $⇒x=\frac{2y-3}{6}$ so $f^{-1}=\frac{2x-3}{6}$