If a/b = 1/7, b/c = 3, c/d = 2/3, d/e = 2 and e/f = 1/2, then what is the value of abc/def ?  Pick one.
A) 72/21 B) 27/85 C) 34/47 D) 13/81 E) 16/21
Say a = 1. Then:   a/b = 1/7 --&gt; b = 7;   b/c = 3 --&gt; c = 7/3;   c/d = 2/3 --&gt; d = 7/2;   d/e = 2 --&gt; e = 7/4;   e/f = 1/2 --&gt; f = 7/2.   abc/def = (1*7*7/3)/(7/2*7/4*7/2) = 16/21.   Answer: 16/21.
<result>E</result>
If a/b = 1/7, b/c = 3, c/d = 2/3, d/e = 2 and e/f = 1/2, then what is the value of abc/def ?