-3x+7y=-16 and -9x+5y=16
The coefficients of x are -3 and -9. These should be identical so we may apply the practice of elimination.
Let's take the first equation...
Let's multiply both sides by 3...
Let's subtract this from the second equation...
The x is eliminated.
Let's plug this into either equation to establish the value of x. I randomly select the first...
Let's add 28 to both sides...
Let's divide both sides by -3...
Let's plug both values into the second equation to verify results...
A negative number multiplied by a negative number has a positive result...