101 students brought mineral water and fruit to the spring outing, among them 78 brought mineral water and 71 brought fruit. How many people brought both mineral water and fruit?
101个同学带着矿泉水和水果去春游，其中带矿泉水的有78人，带水果的有71人，既带矿泉水又带水果的有多少人？
<gadget id="calculator">71 - 101</gadget>
<output>-30</output>

<gadget id="calculator">78 + (-30)</gadget>
<output>48</output>

<result>48</result>