A football is 42 yuan, Xiaoqiang bought 2 footballs, and gave the salesperson 100 yuan, how much should he get back?
一个足球42元，小强买了2个足球，给售货员100元，应找回多少钱？
<gadget id="calculator">42 * 2</gadget>
<output>84</output>

<gadget id="calculator">100 - 84</gadget>
<output>16</output>

<result>16</result>