×Since both equations are in the same variable
'y ' :. y=y
Let y=y be y1=y2
x^2+2x-9=9-x
×Solving the equation gives x=3 , x=-6
(Let x=3 be x1=3 and x=-6 be x2=-6)
×Substitute the value of x into the equations in y variables
(Both values of x, ie. 3 and -6 will satisfy the equation)
Hence the sum of X and Y values is x1+y1 or x2+y2
ie. x1 +y1
3+6= 9
ie.x2+y2
-6+15=11
In a nutshell, the sum of the X and Y value is 9 and/or 11
