A is twice as good a workman as B and they took 10 days together to do the work B alone can do it in.	Choose one.
A) 25 days	B) 88 days	C) 30 days	D) 11 days	E) 13 days

Rationale: wc = 2 : 1 2 x + x = 1 / 10 x = 1 / 30 = > 30 days answer : c
Answer: C