Economic sim Help

I need help subtracting stone from your bank when you end turn
Link: http://www.flowlab.io/game/play/373877

The simplest way to subtract a number is it add a negative number. For example, to subtract “2”, send the value “-2” to the “+” input of a Number. Does that make sense?

If you need to do something more sophisticated than just add/subtract values, you could use an expression instead.

I am trying to get a behavior subtract between three objects in varying amounts, and I am having trouble doing so. One object submits a number, than you press a different button, and then it subtracts a number in a different location.