There are 420 boys in primary school, more girls than boys (1/5), how many fewer boys than girls?
小学有男生420人，女生比男生多(1/5)，男生比女生少多少人？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">420 * (1/5)</gadget>
<output>84</output>

<result>84</result>