A and B rent a pasture for 11 months and A puts in 80 cows for 7 months. How many cows can B put in for the remaining 4 months, if he ( B ) pays half as much as A ?

70

Let the rent for one cow = Rs.1/pm

Then, rent for each partners = no. of cows × time

              A     :     B

No.   :   80    :     x

Time :    7     :     4

-------------------------

Rent :  560   :    4x

 So ATQ,

B paid half the rent paid by A = \(\frac{560}{2}\) = 280

⇒ 4x = 280

⇒ x = 70

Therefore, B puts in 70 cows for the rest 4 months.