1. **State the problem:** We have a triangle with angles 43°, 35°, and an angle labeled as 3x. We need to find the value of $x$. 2. **Recall the triangle angle sum rule:** The sum of the interior angles of any triangle is always 180°. So, $$43 + 35 + 3x = 180$$ 3. **Simplify the equation:** $$78 + 3x = 180$$ 4. **Isolate $x$:** $$3x = 180 - 78$$ $$3x = 102$$ 5. **Solve for $x$:** $$x = \frac{102}{3} = 34$$ **Final answer:** $$x = 34^\circ$$