There are 40 students in the third class of the sixth year. Girls account for 2/5 of the total number of the class. Later, some girls were transferred in. This is the number of girls accounting for the total number of students (3/7). How many students?
六年三班有学生40人，女生占全班总人数的(2/5)，后来又转进若干名女生，这是女生人数占总人数的(3/7)，六年三班现有学生多少人？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 - (3/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(3/5) / (4/7)</gadget>
<output>21/20 = around 1.05</output>

<gadget id="calculator">40 * (21/20)</gadget>
<output>42</output>

<result>42</result>