Among 100 passengers, 60 understand English, 50 understand Korean, and 25 understand both English and Korean. How many people understand neither English nor Korean?
100名旅客中，有60人懂英语，有50人懂韩语，既懂英语又懂韩语的有25人，那么既不懂英语又不懂韩语的有多少人．
<gadget id="calculator">50 - 25</gadget>
<output>25</output>

<gadget id="calculator">60 + 25</gadget>
<output>85</output>

<gadget id="calculator">100 - 85</gadget>
<output>15</output>

<result>15</result>