Answer
$$g=-7\quad \mathrm{or}\quad \:g=-\frac{7}{3}$$
Work Step by Step
Since the value inside the absolute value can be positive or negative and get the same number, we must consider both options. Doing this, we find:
$$3g+14=-7\quad \mathrm{or}\quad \:3g+14=7 \\ g=-7\quad \mathrm{or}\quad \:g=-\frac{7}{3}$$