There are 21 boys in Class 1 of Guangming Primary School, and the number of girls is as many as boys (6/7). How many people are there in the class?
光明小学六1班有男生21人，女生的人数是男生的(6/7)，全班有多少人？
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">21 * (6/7)</gadget>
<output>18</output>

<gadget id="calculator">21 + 18</gadget>
<output>39</output>

<result>39</result>