6. Boys in class 2 account for 4/7 of the whole class. How many girls are boys in this class?
六2班男生占全班人数的(4/7)，这个班女生是男生人数的多少．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) / (4/7)</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>