A couple who own an appliance store discover that if they advertise a sales discount of 10% on every item in the store, at the end of one month the number of total items sold increases 10%. Their gross income from sales for one month decreases by what percent?
Select the correct option:
A) 1%  B) 3%  C) 5%  D) 7%  E) 9%
Let P be the original price and let x be the number of items sold originally.   The original income is P*x.   After the changes, the income is 0.9P*1.1x = 0.99*(P*x), a decrease of 1%.   The answer is 1%.0.9 *1.1= 
<gadget id="calculator">0.9 *1.1</gadget>
<output>0.99</output>
0.99*(P*x), a decrease of 1%.   The answer is 1%.
<result>A</result>
A couple who own an appliance store discover that if they advertise a sales discount of 10% on every item in the store, at the end of one month the number of total items sold increases 10%. Their gross income from sales for one month decreases by what percent?