1. **State the problem:** We are given three angles on a straight line labeled as $3x^\circ$, $x^\circ$, and $2x^\circ$. We need to find the value of $x$. 2. **Formula and rule:** The sum of angles on a straight line is always $180^\circ$. Therefore, we can write the equation: $$3x + x + 2x = 180$$ 3. **Combine like terms:** $$6x = 180$$ 4. **Solve for $x$:** Divide both sides by 6: $$\cancel{6}x = \frac{180}{\cancel{6}}$$ $$x = 30$$ 5. **Conclusion:** The value of $x$ is $30$ degrees.