Set 3: Systems of Equations (Advanced)

Choice C is correct. Choice C is the correct answer. Multiply first by 3 and second by 5 to eliminate $y$. Step 1: Multiply: 18x - 15 y = 21$$20x + 15 y = 125 Step 2: Add: 38x = 146$x = \frac{146}{38} = \frac{73}{19}$$ Non-integer. - First: $6(\frac{7}{2}) - 5(4) = 21 - 20 = 1 \neq 7$ - Second: $4(\frac{7}{2}) + 3(4) = 14 + 12 = 26 \neq 25$ First: $6(\frac{7}{2}) - 5 y = 21 - 5 y$. Add: 38x = 133$x = 3.5 = \frac{7}{2}$Substitute:$6(\frac{7}{2}) - 5 y = 1 \Rightarrow 21 - 5 y = 1 \Rightarrow y = 4$$ Strategic Tip: LCM of 5 and 3 is 15. Other choices are incorrect based on calculation.