Less than 50 students in the sixth grade participated in the "Red Journey" tour. They were divided into four groups. The first group accounted for (1/7) of the total number, and the second group accounted for (1/6) ), the number of people in the third group accounts for (1/3) of the total number of people, and how many people are in the fourth group.
六年级有不到50名同学参加"红色之旅"旅游，共分成四个小组，第一组的人数占总人数的(1/7)，第二组的人数占总人数的(1/6)，第三组的人数占总人数的(1/3)，第四组有多少人．
<gadget id="calculator">13 / 42</gadget>
<output>13/42 = around 0.309524</output>

<gadget id="calculator">42 * (13/42)</gadget>
<output>13</output>

<result>13</result>