If there are more boys than girls in a class (1/4), how much fewer girls are there than boys?
一个班的男生比女生多(1/4)，则女生比男生少多少．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>