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 25%. Their gross income from sales for one month increases by what percent? Pick one:	A) 5%	B) 7.5%	C) 10%	D) 12.5%	E) 15%
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*1.25x = 1.125*(P*x), an increase of 12.5%.   The answer is 12.5%.0.9 *1.25= 
<gadget id="calculator">0.9 *1.25</gadget>
<output>1.125</output>
1.125*(P*x), an increase of 12.5%.   The answer is 12.5%.
<result>D</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 25%. Their gross income from sales for one month increases by what percent?