Given that a and b are reciprocals of each other, what is the product of ((a)/3)*((b)/7).
已知a和b互为倒数，那么((a)/3)*((b)/7)的积是多少．
<gadget id="calculator">1 / 21</gadget>
<output>1/21 = around 0.047619</output>

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