the function is already in slope-intercept form (y=mx+b). B is the y intercept and mx is the slope. The equation y=x+4 means that there is a y intercept of 4 and a slope of 1. So, y intercept is when x is equal to 0 which means one of your points will be (0,4). The next point will be 1 unit up and 1 unit to the right of the point (0, 4) and the third point will be 1 unit down and 1 unit to the left of (0, 4). This gives you the points (1, 5) and (-1, 3)
