If 40 sheep eat 40 bags of grass in 40 days. In how many days one sheep will eat one bag of grass? Choose the most appropriate option
A) 1	B) 20	C) 40	D) 80	E) 70

Rationale: explanation : let the required number of days be x . less sheep , more days ( indirect proportion ) less bags , less days ( direct proportion ) sheep 1 : 40 : : 40 : x bags 40 : 1 1 x 40 x x = 40 x 1 x 40 x = 40 . answer : c
Answer: C