Set 7: Linear Equations (Advanced)

Choice D is correct. Choice Ahoice D is the correct answer. 1. Subtract 3 x: $7x - 7 = 21$ 2. Add 7: $7x = 28$ 3. Divide by 7: $x = 4$ 4. Verify: $10(4) - 7 = 33$ and $3(4) + 21 = 33$ ✓ Choice Ahoice D is incorrect because it results from an error in the solution process. Choice Ahoice C is incorrect because it results from an error in the solution process. Choice Ahoice C is incorrect because it results from an error in the solution process.