What do you notice about the sliders and their numbers?
If you were to label the horizontal slider what would you label each side?
What would you label the vertical sliders?
What would the rule look like if the slider went to 100?
What would you do if the rule was [math]\left(x,y\right)\rightarrow\left(\frac{4}{5}x,\frac{4}{5}y\right)[/math]?