Question 361734
c +p =100,
2c + 4p = 270.  The top equation gives c = 100-p.  Substituting into the bottom equation, 2(100-p) + 4p = 270.
200-2p+4p = 270,
2p = 70,
p = 35, so there are 35 pigs, and 100-35 = 65 chickens.