Verified answer

first we solve the system with equality to see where the lines cross:

x+y = 1; -x+y = 3;

--> x=-1; y= 2;

4. x+y<1

y>x+3

solution is in the V to the left of the point

2y-x = 4; -2y+x = 1;

lines do not cross, solution is

outside the two lines

5. 2y≥x+4

x-2y≥1

y-x = 4; -y+x = 3;

lines do not cross, solution is

between the two lines

6. y≤x+4

x-y≤3