plotting a straight line with slope and a single point

Greetings,

I am trying to plot the following items with given slope and x,y coordinate (single points)

%%%Y-Values
Stress_fail_GF=2.1;
Stress_fail_AF=2.8;
Stress_fail_Matrix=0.1;

%%%X-Value
Strain_fail_GF=.0054;
Strain_fail_AF=.021;
Strain_fail_Matrix=.33;

%%%Modulus - Slope 
GF_Modulus=Stress_fail_GF/Strain_fail_GF;
AF_Modulus=Stress_fail_AF/Strain_fail_AF;
Matrix_Modulus=Stress_fail_Matrix/Strain_fail_Matrix;

%%% I tested the following, but it provides a blank graph 
x = Stress_fail_GF;
m = GF_Modulus;
b = Strain_fail_GF;
y = m*x + b;
figure(1)
plot(x, y)
grid