Answer:
60 chickens
Step-by-step explanation:
We assume the 140 refers to the number animals (heads, noses, bodies, whatever). If all of those were chickens, there would be 280 legs. There are 160 legs more than that.
Since each pig that replaces a chicken adds 2 legs, there must be 160/2 = 80 pigs. That leaves 140 -80 = 60 chickens.
