Y = mx + c where m is the gradient (y/x) and c is the y intercept. Plot those coordinates into the equation ; -8 = m x 0 + c. C = -8. The line intercepts the graph at 0,-8 so it's a flat straight line as the gradient is 0. Therefore, all you have to do is y = mx + c, where m = 0 and c = anything apart from -8
