Choice C is the correct answer. Since $x = 4y$ is already isolated, we can substitute it into the second equation.

Step 1: Substitute $x = 4y$ into $2x + 3y = 55$: $2(4y) + 3y = 55$$8y + 3y = 55$$11y = 55$$y = 5$

Step 2: Find $x$ using $x = 4y$: $x = 4(5) = 20$

Solution: $(20, 5)$

Verification: $2(20) + 3(5) = 40 + 15 = 55$ ✓

💡 Strategic Tip: When a variable is isolated, substitution is straightforward and efficient.

Choice A is incorrect because$2(16) + 3(4) = 32 + 12 = 44 \ eq 55$.

Choice B is incorrect because$2(24) + 3(6) = 48 + 18 = 66 \ eq 55$.

Choice D is incorrect because$2(12) + 3(3) = 24 + 9 = 33 \ eq 55$.