Assume that 20 cows and 40 goats can be kept for 10 days for Rs.460. If the cost of keeping 5 goats is the same as the cost of keeping 1 cow, what will be the cost for keeping 50 cows and 30 goats for 12 days?

A. Rs.1104
B. Rs.1000
C. Rs.934
D. Rs.1210

Assume that cost of keeping a cow for 1 day = c ,

cost of keeping a goat for 1 day = g
Cost of keeping 20 cows and 40 goats for 10 days = 460

Cost of keeping 20 cows and 40 goats for 1 day = 460/10 = 46

=> 20c + 40g = 46

=> 10c + 20g = 23 —(1)

Given that 5g = c
Hence equation (1) can be written as 10c + 4c = 23 => 14c =23

=> c=23/14
cost of keeping 50 cows and 30 goats for 1 day

= 50c + 30g

= 50c + 6c (substituted 5g = c)

= 56 c = 56×23/14

= 92
Cost of keeping 50 cows and 30 goats for 12 days = 12×92 = 1104