Question 76480
The given set of equations are:  


x + y = 3


x + y = -1 


The graph these set of equations are:  

{{{graph( 300, 200, -10, 10, -10, 10, 3 - x, -1 - x)}}} 


Here from the graph we observe that both the equations are parallel to each other and thus have no common solution. 

Hence, the solution.