"Articificially creat a data set {x_i,y_i} with approximately linear relatition. Estimate the best fit for this data set "
SetDirectory[NotebookDirectory[]];
m=2.5;c=-7.1;
y[x_]:=m*x+c;
txy=Table[{x+(2Random[]-1)^3,y[x]+(2Random[]-1)^3},{x,-12,7.5,0.12}];
lpttxy=ListPlot[txy,AxesLabel->{"x","y"}]
Export["data_for_linear_fit.dat",txy];