1. **State the problem:** Solve the equation $X + (X + 170) = 200$ for $X$. 2. **Write the equation:** $$X + (X + 170) = 200$$ 3. **Simplify the left side by combining like terms:** $$X + X + 170 = 200$$ $$2X + 170 = 200$$ 4. **Isolate the term with $X$ by subtracting 170 from both sides:** $$2X + \cancel{170} - \cancel{170} = 200 - 170$$ $$2X = 30$$ 5. **Solve for $X$ by dividing both sides by 2:** $$\frac{2X}{\cancel{2}} = \frac{30}{\cancel{2}}$$ $$X = 15$$ 6. **Final answer:** $$X = 15$$