In a dairy farm, 40 cows eat 40 bags of husk in 40 days. In how many days one cow will eat one bag of husk? Choose the correct answer: A) 1 B) 1 / 40 C) 40 D) 80 E) 1 / 80

Rationale: "assume that in x days , one cow will eat one bag of husk . more cows , less days ( indirect proportion ) more bags , more days ( direct proportion ) hence we can write as cowsbags 40 : 11 : 40 ⎫ ⎭ ⎬ : : x : 40 ⇒ 40 × 1 × 40 = 1 × 40 × x ⇒ x = 40 answer : c"
Answer: C