There are 378 boys and 231 girls in the first grade of elementary school, and 225 of them wear red scarves. How many people don't wear red scarves?
小学一年级有男生378人，女生231人，有225人带了红领巾，还有多少人没有带红领巾？
<gadget id="calculator">231 - 225</gadget>
<output>6</output>

<gadget id="calculator">378 + 6</gadget>
<output>384</output>

<result>384</result>