It is known that the number A is (4/7) of the average of C and B, then the number of A is ((())/(())) of the average of A, B and C.
已知甲数是丙、乙平均数的(4/7)，那么甲数是甲、乙、丙平均数的((())/(()))．
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>