There are 178 boys and 146 girls in the first grade of No. 81 Middle School. There are 309 people who have checked their bodies, how many people have not checked their bodies?
第八十一中学一年级有男生178人，女生146人．已经检查身体的有309人，没检查身体的有多少人？
<gadget id="calculator">146 - 309</gadget>
<output>-163</output>

<gadget id="calculator">178 + (-163)</gadget>
<output>15</output>

<result>15</result>