The sales tax rate in Bergville is $$6\textbackslash\%$$. During a sale at the Bergville Coat Closet, the price of a coat is discounted $$20\textbackslash\%$$ from its ＄$$90.00$$ price. Two clerks, Jack and Jill, calculate the bill independently. Jack rings up ＄$$90.00$$ and adds $$6\textbackslash\%$$ sales tax, then subtracts $$20\textbackslash\%$$ from this total. Jill rings up ＄$$90.00$$, subtracts $$20\textbackslash\%$$ of the price, then adds $$6\textbackslash\%$$ of the discounted price for sales tax. What is Jack's total minus Jill's total? 
Overseas Competition->Knowledge Point->Word Problem Modules->Word Problems in Economics->Complex Money Word Problems
The price Jacks rings up is $$(90.00)(1.06)(0.80)$$. The price Jill rings up is $$(90.00)(0.80)(1.06)$$. By the commutative property of multiplication, these quantities are the same, and the difference is $$(\text{C})$$＄$$0$$. 