#### Answer

$\frac{-3n}{4}$

#### Work Step by Step

By inspection, we see that the LCM is $12$. Therefore, we create a common denominator to obtain:
$\frac{7n}{12}-\frac{4n}{3}$
$=\frac{7n-4(4n)}{12}$
$=\frac{7n-16n}{12}$
$=\frac{-9n}{12}$
$=\frac{-3n}{4}$