A, B and C rent a pasture. If A puts 10 oxen for 7 months, B puts 12 oxen for 5 months and C puts 15 oxen for 3 months for grazing and the rent of the pasture is Rs. 280, then how much amount should C pay as his share of rent?  Choose the correct choice from the following answers
A) 35	B) 45	C) 25	D) 72	E) 55

Rationale: a : b : c = 10 × 7 : 12 × 5 : 15 × 3 = 2 × 7 : 12 × 1 : 3 × 3 = 14 : 12 : 9 amount that c should pay = 280 × 9 / 35 = 8 × 9 = 72 answer is d
Answer: D