The school needs to move 22 tables for the federation, one for every two students, and now there are 15 students, how many more students are needed to move all at once?
学校开联合会需要搬22张桌子，每两名同学搬一张，现在有15名同学，还需要多少名同学才能一次搬完？
<gadget id="calculator">22 * 2</gadget>
<output>44</output>

<gadget id="calculator">44 - 15</gadget>
<output>29</output>

<result>29</result>