Hi Andrew,

You link your minus and plus symbol to an action that does an assign using the variable that holds the value on your number 2. And you add one more or one less depending if its + or -, the button it was clicked. For example, your action linked to + should look like this (in my example the variable is Number):

In the case of action linked to -, it should of course be Number - 1 in the second part of the assign.

Kind Regards,
João