There are 25 questions in a test paper, 4 points are awarded for each correct answer, and 1 point is deducted for each wrong answer or no answer. A student gets 60 points in total. How many questions did he answer correctly?
一张试卷有25道题，答对一题得4分，答错或不答均倒扣1分，某同学共得60分，他答对了多少道题？
<gadget id="calculator">25 * 4</gadget>
<output>100</output>

<gadget id="calculator">100 - 60</gadget>
<output>40</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">40 / 5</gadget>
<output>8</output>

<gadget id="calculator">25 - 8</gadget>
<output>17</output>

<result>17</result>