Set 3: Linear Equations (Advanced)

Choice C is correct. Choice D is the correct answer. We divide by the coefficient to isolate $x$. 1. Start with the equation: $2x = 18$ 2. Divide both sides by 2: $x = \frac{18}{2}$ 3. Simplify: $x = 9$ 4. Verify: $2(9) = 18$ ✓ Even Number Division: Dividing even numbers by 2 is straightforward—half of 18 is 9. Choice D is incorrect because this results from subtracting: $18- 2 = 16$. Subtraction is not the inverse of multiplication. Choice A is incorrect because this comes from adding: $18+ 2 = 20$. Addition doesn't undo multiplication. Choice C is incorrect because this results from multiplying: $18\times 2 = 36$. This doubles the product instead of isolating $x$.