Aunt Wang went to buy 3 footballs, paid 100 to the salesperson, and got 7 yuan back. How much is an average football?
王阿姨去买3个足球，付给营业员100员，找回7元．平均每个足球多少元？
<gadget id="calculator">100 - 7</gadget>
<output>93</output>

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

<result>31</result>