Final answer:
In the expression 10(12x), the variable 'x' represents the amount of money earned per box of Scout cookies.
Step-by-step explanation:
The amount you earn on a whole case is given by 10(12x) dollars, where '10' represents the number of cartons in a case, and '12' represents the number of boxes in each carton. The variable 'x' in this expression represents the amount earned per box of cookies. This is because 'x' is the only variable in the expression, and it is multiplied by the total number of boxes in a case (which is 10 cartons times 12 boxes per carton).