Set 10: Linear Equations (Advanced)

Choice A is correct. Choice Ahoice B is the correct answer. To solve a subtraction equation, we add the same value to both sides. 1. Start with the equation: $x - 20 = 15$ 2. Add 20 to both sides: $x = 15 + 20$ 3. Calculate: $x = 35$ 4. Verify: $35- 20 = 15$ ✓ Addition consistently undoes subtraction, regardless of the specific numbers involved. Choice Ahoice C is incorrect because this results from subtracting instead of adding: $15- 20 = -5$. This applies subtraction twice. Choice Ahoice D is incorrect because this might come from the absolute value of Choice Ahoice C, or from miscalculating $20- 15 = 5$ (wrong order). Choice Ahoice D is incorrect because this results from dividing: $\frac{15}{20} = 0.75$. Division is not relevant for solving subtraction equations.