#### Answer

$ c=2$

#### Work Step by Step

MVT states that $ f'(c)=\frac{f(b)-f(a)}{b-a}$
Then, $2c-4=\frac{[(3-1)(3-3)]-[(1-1)(1-3)]}{3-1}$
$\implies 2c-4=0$
$\implies 2c=4$
$\implies c=2$
$ c=2$ lies in the interval $(1,3)$ and is a point that satisfies the conclusion of the MVT in the given function.