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 12%. Their gross income from sales for one month increases by what percent?
Options
A) 0.4% B) 0.8% C) 2% D) 4% E) 8%
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*1.12x = 1.008*(P*x), an increase of 0.8%.   The answer is 0.8%.0.9 *1.12= 
<gadget id="calculator">0.9 *1.12</gadget>
<output>1.008</output>
1.008*(P*x), an increase of 0.8%.   The answer is 0.8%.
<result>B</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 12%. Their gross income from sales for one month increases by what percent?