There are 100 people, 10 of them do not know English or French, 75 people know English, and 83 people know French, so how many people know both English and French?
有100人，其中10人不懂英语，也不懂法语，有75人懂英语，83人懂法语，那么既懂英语又懂法语的有多少人．
<gadget id="calculator">100 - 10</gadget>
<output>90</output>

<gadget id="calculator">83 - 90</gadget>
<output>-7</output>

<gadget id="calculator">75 + (-7)</gadget>
<output>68</output>

<result>68</result>