Mike needed a new pair of jeans.  When he got to the mall he saw that his favorite jeans were advertised 25% off.  The original price of the jeans was $40.  How much money will Mike have left over if he pays with a $50.00 bill?
The jeans cost $40 and are sale for 25% off so 40 * .25 = $
<gadget id="calculator">40*.25</gadget>
<output>10</output>
10.00 discount.
Take the original cost of the jeans and subtract the discount so 40-10 = $
<gadget id="calculator">40-10</gadget>
<output>30</output>
30.00.
Mike pays with a $50 bill and the final cost of the jeans is $30 so 50-30 = $
<gadget id="calculator">50-30</gadget>
<output>20</output>
20.00 left.

<result>20</result>