Answer
$-5\sqrt 3$
Work Step by Step
We have
$$
2\sqrt{12}-3\sqrt{27}= 2\sqrt{3\times2^2}-3\sqrt{3\times3^2}\\
=4\sqrt 3-9\sqrt 3
.$$
Now, we simplify by factoring out $\sqrt 3$ and then combine the like terms as follows:
$$
4\sqrt 3-9\sqrt 3=(4-9)\sqrt 3=-5\sqrt 3
.$$
