There are 40 students in Class 1, and there are only two questions in a math test. As a result, 10 students in the class are all correct. If 25 people get the first question right and 18 people get the second question wrong, how many people get both questions wrong?
六1班有40人，一次数学测验只有两道题，结果全班有10人全对．第一题有25人做对，第二题的18人做错，那么两道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>