Answer: 3
Explanation:
To use the elimination method, we need the two equations to have opposite leading coefficients. Right now, we have 9 and -3. Multiplying the second equation by 3 gives us 9 and -9, which is what we need.
9x - 7y = -3
-3x + 5y = 9 <----------------------- Multiply by 3 on both sides.
9x - 7y = -3
-9x + 15y = 27 <----------------------- Multiply by 3 on both sides.