A, B, and C have some books, 200 of which belong to A and 750 do not belong to B, how many books does C have?
甲乙丙三人有一些书，其中200本是甲的，750本不是乙的，则丙有多少本？
<gadget id="calculator">750 - 200</gadget>
<output>550</output>

<result>550</result>