A is B's (5/8), B is C's (4/5), given that C is 20, find the size of A.
甲是乙的(5/8)，乙是丙的(4/5)，已知丙是20，求甲的大小．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">20 * (4/5) * (5/8)</gadget>
<output>10</output>

<result>10</result>