The school band recruited 42 new students, of which 25 could play the violin, 22 could play the electronic organ, and 3 could neither. How many people can do both.
学校乐队招收了42名新学员，其中会拉小提琴的有25名，会弹电子琴的有22名，两项都不会的有3名．两项都会的有多少名．
<gadget id="calculator">25 + 22</gadget>
<output>47</output>

<gadget id="calculator">42 - 3</gadget>
<output>39</output>

<gadget id="calculator">47 - 39</gadget>
<output>8</output>

<result>8</result>