Students in middle and senior grades listen to reports given by scientists. There were 84 participants in the middle grades, three times the number of participants in the senior grades. How many people listened to the report? What is the column
中、高年级同学听科学家作报告．中年级有84人参加，是高年级参加人数的3倍．听报告的一共有多少人？列式为多少
<gadget id="calculator">84 / 3</gadget>
<output>28</output>

<gadget id="calculator">28 + 84</gadget>
<output>112</output>

<result>112</result>