There are 172 boys and 128 girls in Midong Primary School. 250 people have had their health checks. How many people have not had their health checks?
弥东小学有男生172人，女生128人，已经检查身体的250人，没检查身体的有几人？
<gadget id="calculator">172 + 128</gadget>
<output>300</output>

<gadget id="calculator">300 - 250</gadget>
<output>50</output>

<result>50</result>