Mom bought 2 coats on the street, each for 45 yuan, and paid 100 yuan, how much should I get back?
妈妈在街上买了2件上衣，每件45元，付出100元，应找回多少元？
<gadget id="calculator">2 * 45</gadget>
<output>90</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<result>10</result>