Answer:
Option C
Explanation:
Let H, C, B and K represent the number of hens, cows, bullocks and keepers respectively. Then, as given, we have:
H + C + B + K < 50 .......(i)
C = 2B .........(ii)
C = H .........(iii)
$K= \frac{H+C+B}{10}$ .........(iv)
From , (ii),(iii),(iv), we have:
10K = H + C+ B <=> 10K = 2C + B = 2 X 2B <=> 10K = 5B
B = 2K
So, B = 2K ,C = 2B =4K , H = C 4K
Total number of heads = H + C + B + K .
Total number of legs = 2H + 4C + 4B + 2K
(2H + 4C + 4B + 2K) - (H + C + B + K ) = 69
H + 3C + 3B + K = 69
4K + 12K + 6K + K =69
K = 3
Hence number of cows = C = 4K =(4 X 3) = 12