There are 48 students in class 31, 18 of them can ride bicycles, 15 can swim, 8 can do both, and how many can neither?
三1班有学生48人，其中会骑车自行车的有18人，会游泳的有15人，两样都会的有8人，两样都不会的有多少人？
<gadget id="calculator">15 - 8</gadget>
<output>7</output>

<gadget id="calculator">18 + 7</gadget>
<output>25</output>

<gadget id="calculator">48 - 25</gadget>
<output>23</output>

<result>23</result>