There are 20 soccer balls, 4 less than twice as many basketballs. How many basketballs are there?
足球有20个，比篮球的2倍少4个，篮球有多少个．
<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<result>12</result>