Question 1204783
you can use any graphing calculator 
OR 
Plot the points and draw the line

x-y=3

y=x-3
Get y values from different values of x

For 

x=1 , y= -2 (1,-2)
x=3 , y=0 (3,0)
x=-3, y=-6 (-3,-6)
Plot the points and draw the line 

 *[illustration line.png].