The teacher wants to buy 3 footballs, gives the salesperson 100 yuan, and gets back 7 yuan. How much is each football?
老师要买3个足球，给售货员100元，找回7元，每个足球多少元？
<gadget id="calculator">100 - 7</gadget>
<output>93</output>

<gadget id="calculator">93 / 3</gadget>
<output>31</output>

<result>31</result>