The school bought 286 boxes of white chalk, 158 boxes of colored chalk, and 166 boxes of both types of chalk. How many boxes of chalk are there?
学校买来白色粉笔286盒，彩色粉笔158盒，两种粉笔公用去166盒，还有多少盒粉笔？
<gadget id="calculator">158 - 166</gadget>
<output>-8</output>

<gadget id="calculator">286 + (-8)</gadget>
<output>278</output>

<result>278</result>