第14 步：斜率的公式是斜率等于运行时的上升。让我们这样做吧！
To navigate the page using the TAB key, first press ESC to exit the code editor.
stage.set_axis(100)
stage.create_grid_overlay(10, "grey")
stage.set_background("soccerfield")
ballx = -80
bally = random.randint(-100,100)
# sprite = codesters.Sprite("image", x, y)
ball = codesters.Sprite("soccerball", ballx, bally)
netx = 90
nety = random.randint(-100,100)
# sprite = codesters.Sprite("image", x, y)
net = codesters.Sprite("soccernet", netx, nety)
net.flip_right_left()
#sprite = codesters.Line(x-start, y-start, x-end, y-end, "color")
line = codesters.Line(ballx, bally, netx, nety, "blue")
slopeguess = float(line.ask("What is the slope of this line?"))
rise = nety - bally
run = netx - ballx
