x-y= 12

The sum of the two equations is equal to (x+y)+(x-y)= 18+ 12.

Decomposition into 2x=30 x= 15.

If x= 15 is brought into the equation x+y= 18, then y=3.

2x+y= 15 x-2y= 12 and other complex points are 2 * (2x+y)+(x-2y) =15 * 2+12, then x=8.4 is substituted into the equation y =-/.