Mom bought 5 towels at 8.5 yuan each. She paid the salesperson 100 yuan, how much should she get back?
妈妈买了5条毛巾，每条8.5元．她付给售货员100元，应找回多少元？
<gadget id="calculator">8.5 * 5</gadget>
<output>42.5</output>

<gadget id="calculator">100 - 42.5</gadget>
<output>57.5</output>

<result>57.5</result>