How to go about solving this inequality question? $\cos(3x-\pi/3) \leq (1/2).$ 
Here is what I have done so far...
Let $3x-\pi/3 = X$. So I need to solve $\cos(X) \leq 1/2$. Which is all $X$ from $\pi/3$ to $5\pi/3$, so--
$\pi/3 \leq X \leq 5\pi/3 \quad\longrightarrow\quad \pi/3 \leq 3x-\pi/3 \leq 5\pi/3.$
So should I now solve for $x$? or...

From here...
$$\frac{\pi}{3} \leq 3x - \frac{\pi}{3} \leq \frac{5\pi}{3} $$
Add $\frac{\pi}{3}$ to each part of the inequality to arrive at 
$$\frac{2\pi}{3} \leq 3x \leq 2\pi $$
Then divide each part by $3$. 
