For this case we have that the pigs have 4 legs while the hens have 2.
We propose a system of equations:
x: Variable representing the number of pigs
y: Variable representing the number of chickens

We multiply by -4 the first equation:

We add the equations:

So, there are 12 chickens.

There are 25 pigs.
ANswer:
25 pigs
12 chickens
Option C