The number of girls accounts for (4/7) the number of students in the whole grade, and there are 40 more boys than girls (2/3). How many girls are there?
女生人数占全年级人数的(4/7)，男生比女生的(2/3)多40人，女生有多少人？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(4/7) * (2/3)</gadget>
<output>8/21 = around 0.380952</output>

<gadget id="calculator">1 - (4/7) - (8/21)</gadget>
<output>1/21 = around 0.047619</output>

<gadget id="calculator">40 / (1/21)</gadget>
<output>840</output>

<gadget id="calculator">840 * (4/7)</gadget>
<output>480</output>

<result>480</result>