A is twice as good a workman as B and they took 7 days together to do the work B alone can do it in?
Choices:
A) 25 days
B) 88 days
C) 21 days
D) 11 days
E) 13 days
W21 days = 2:1   2x + x = 1/7   x = 1/21 =&gt; 21 days   Answer: 21 days
<result>C</result>
A is twice as good a workman as B and they took 7 days together to do the work B alone can do it in?