There are 38 people taking the exam, 25 people are excellent in Chinese, 23 people are excellent in mathematics, and 15 people are excellent in both subjects. How many people did not get excellent grades in both subjects?
有38人参加考试，语文成绩优秀的有25人，数学成绩优秀的有23人，两门成绩都优秀的有15人．有多少人两门成绩都没获优秀．
<gadget id="calculator">23 - 15</gadget>
<output>8</output>

<gadget id="calculator">25 + 8</gadget>
<output>33</output>

<gadget id="calculator">38 - 33</gadget>
<output>5</output>

<result>5</result>