Uncle Wang bought 3 basketballs at 28 yuan each. He paid 100 yuan, how much should he get back?
王叔叔买了3个篮球，每个28元．他付了100元，应找回多少元？
<gadget id="calculator">3 * 28</gadget>
<output>84</output>

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

<result>16</result>