There are 39 softballs, 17 fewer footballs than softballs, half as many basketballs as footballs, how many basketballs are there?
垒球有39个，足球比垒球少17个，篮球的个数是足球的一半，篮球有多少个．
<gadget id="calculator">39 - 17</gadget>
<output>22</output>

<gadget id="calculator">22 / 2</gadget>
<output>11</output>

<result>11</result>