Graphical representation of simplex method

I've solved the problem by hand and confirmed my solution in Matlab to this problem, but I cant figure out the contour plot for it

My code for the plot is:

 c=[-10;-8];
 A=[.4 .5;.6 .5;1 0; 0 1];
 b=[100 80 70 110]';
[X1,X2]=meshgrid(-1:0.1:4);
[C,h]=contour(X1,X2,c(1)*X1+c(2)*X2,20); hold on
clabel(C,h); xlabel('x_1'); ylabel('x_2');

contour(X1,X2,-X1,[0 0],'k','LineWidth',2)
contour(X1,X2,-X1,0.01:0.01:0.1,'Color',[.8 .8 .8])
contour(X1,X2,-X2,[0 0],'k','LineWidth',2)
contour(X1,X2,-X2,0.01:0.01:0.1,'Color',[.8 .8 .8])
contour(X1,X2,A(1,1)*X1+A(1,2)*X2-b(1),[0 0],'k','LineWidth',2)
contour(X1,X2,A(1,1)*X1+A(1,2)*X2-b(1),0.01:0.01:0.1,'Color',[.8 .8 .8])
contour(X1,X2,A(2,1)*X1+A(2,2)*X2-b(2),[0 0],'k','LineWidth',2)
contour(X1,X2,A(2,1)*X1+A(2,2)*X2-b(2),0.01:0.01:0.1,'Color',[.8 .8 .8])
contour(X1,X2,A(3,1)*X1+A(3,2)*X2-b(3),[0 0],'k','LineWidth',2)
contour(X1,X2,A(3,1)*X1+A(3,2)*X2-b(3),0.01:0.01:0.1,'Color',[.8 .8 .8])
contour(X1,X2,A(4,1)*X1+A(4,2)*X2-b(4),[0 0],'k','LineWidth',2)
contour(X1,X2,A(4,1)*X1+A(4,2)*X2-b(4),0.01:0.01:0.1,'Color',[.8 .8 .8])
axis equal

its giving me this:

when I want somthign like: What can I do?