1. **State the problem:** We are given two adjacent angles on a straight line, $3x$ degrees and $(8x + 70)$ degrees, and we want to verify if the equation $3x + (8x + 70) = 180$ is correct. 2. **Formula and rule:** Adjacent angles on a straight line sum to $180^\circ$. This is called the Linear Pair Postulate. 3. **Write the equation:** $$3x + (8x + 70) = 180$$ 4. **Simplify the left side:** $$3x + 8x + 70 = 180$$ $$11x + 70 = 180$$ 5. **Isolate $x$ by subtracting 70 from both sides:** $$11x + \cancel{70} - \cancel{70} = 180 - 70$$ $$11x = 110$$ 6. **Divide both sides by 11:** $$\frac{11x}{\cancel{11}} = \frac{110}{\cancel{11}}$$ $$x = 10$$ 7. **Check the solution:** Calculate each angle: $$3x = 3 \times 10 = 30^\circ$$ $$(8x + 70) = 8 \times 10 + 70 = 80 + 70 = 150^\circ$$ Sum: $$30 + 150 = 180^\circ$$ **Conclusion:** Your equation and steps are correct. The angles sum to $180^\circ$ as expected for a straight line.