For the given equations, (x,y)=(10,−1)
Explanation:[1]XXXX3y=−12x+2
[2]XXXXy=−x+9
While it is not technically necessary, I find it easier to clear the fractions before actually beginning; so multiplying [1] by 2
[3]XXXX6y=−x+4
Substituting (from [2]) (−x+9) for y in [3]
[4]XXXX6(−x+9)=−x+4
Simplifying
[5]XXXX−6x+54=−x+4
[6]XXXX5x=50
[7]XXXXx=10
Substituting (from [7]) 10 for x in [2]
[8]XXXXy=−10+9=−1
