Answer
$\frac{7}{2}x-3$
Work Step by Step
First, look at each term separately using sum/difference rule.
$\frac{d}{dx}(\frac{7}{4}x^2)-\frac{d}{dx}(3x)+\frac{d}{dx}(12)$
Then take derivative using general power rule.
$\frac{7}{4}*2x-3*1+0$