There are only two questions in a math quiz. As a result, 10 people in the class are all correct, 25 people get the first question right, and 18 people get the second question wrong. How many people get both questions wrong?
一次数学小测验中只有两道题，结果全班有10人全对，第一题有25人做对，第二题有18人做错，那么两题都做错的有多少人？
<gadget id="calculator">25 - 10</gadget>
<output>15</output>

<gadget id="calculator">18 - 15</gadget>
<output>3</output>

<result>3</result>