I built this a while ago on Geogebra. I usually use it with mini-whiteboards as a flexible way to do AfL on percentage of an amount. You can select what is shown using the tick boxes, usually revealing the “answer” by ticking the third box – “Show amount”.
If you click the image above, it will open in GeoGebra Tube. If you would rather download the .ggb file, click here.