Set 4: Systems of Equations (Advanced)

Choice C is correct. Choice C is the correct answer. Since $x = 5 y$ is already isolated, we can directly substitute it into the second equation. Step 1: Substitute $x = 5 y$ into $2x + y = 33$: 2(5 y) + y = 33$10y + y = 3311y = 33y = 3$$ Step 2: Find x$using$x = 5 y: $$x = 5(3) = 15$$ Solution: (15, 3)$Verification:$2(15) + 3 = 30 + 3 = 33$✓ Strategic Tip: When a variable is already isolated, substitution is the most efficient method. Choice A is incorrect because$2(10) + 2 = 20 + 2 = 22 \neq 33$. Choice B is incorrect because$2(20) + 4 = 40 + 4 = 44 \neq 33$. Choice D is incorrect because$2(25) + 5 = 50 + 5 = 55 \neq 33$.