Set 7: Linear Equations (Advanced)

Choice B is correct. Choice D is the correct answer. This multiplication equation with friendly numbers makes division straightforward. 1. Start with the equation: $20x = 100$ 2. Divide both sides by 20: $x = \frac{100}{20}$ 3. Simplify: $x = 5$ 4. Verify: $20(5) = 100$ ✓ Mental Math: Think "20 times what equals 100?" Since $20\times 5 = 100$, the answer is 5. Choice A is incorrect because this results from subtracting: $100- 20 = 80$. Subtraction is not the inverse of multiplication. Choice B is incorrect because this comes from adding: $100+ 20 = 120$. Addition doesn't undo multiplication. Choice D is incorrect because this results from multiplying: $100\times 20 = 2000$. This makes the product larger instead of isolating $x$.