There are 8 more balls in the sports room than volleyballs, 3 more footballs than twice as many volleyballs, and 21 balls. How many footballs are there in the sports room?
体育室里皮球比排球多8个，足球的个数比排球的2倍多3个，皮球有21个，体育室里有多少个足球？
<gadget id="calculator">26 + 8</gadget>
<output>34</output>

<result>34</result>