If a and b are reciprocals of each other, then ((a)/3)/(7/(b))=how much.
如果a和b互为倒数，那么((a)/3)/(7/(b))=多少．
<gadget id="calculator">1 / 21</gadget>
<output>1/21 = around 0.047619</output>

<result>1/21 = around 0.047619</result>