Among the 100 tourists, 75 understand French, 83 understand English, and 10 understand neither of these two languages. How many tourists know both French and English?
在100位旅游者中，有75人懂法语，83人懂英语，另有10人这两种语言都不懂．既懂法语又懂英语的旅游者有多少人？
<gadget id="calculator">75 + 83</gadget>
<output>158</output>

<gadget id="calculator">100 - 10</gadget>
<output>90</output>

<gadget id="calculator">158 - 90</gadget>
<output>68</output>

<result>68</result>