There are 45 students in a certain class, 15 of them take part in the math group, 19 take part in the model group, and 11 take part in both groups. So how many people did not participate in either group?
某班有45名学生，其中有15人参加数学小组，19人参加航模小组，有11人两个小组都参加．那么有多少人两个小组都不参加？
<gadget id="calculator">19 - 11</gadget>
<output>8</output>

<gadget id="calculator">15 + 8</gadget>
<output>23</output>

<gadget id="calculator">45 - 23</gadget>
<output>22</output>

<result>22</result>