Use the intercept method for graphing lines:
x-intercept: let y = 0 and find x: x - 0 = -1. Then x = -1, and the x-intercept is (-1,0).
y-intercept: let x = 0 and find y: 0 - y = -1. Then y = 1, and the x-intercept is (0,1).
Plot (0,1) and (-1,0) and draw a straight line thru these two points.
