Solution:
we are given that
Each cow has 4 legs and each chicken has 2 legs.
A boy counts 42 heads and 144 feet.
we have been asked to find how many cows are there?
Let there are x cows and y chicken.
Then we can write
[tex] x+y=42....(i)\\\\\text{Sum of Heads}\\\\4x+2y=144\\\\\text{Sum of feet }\\\\\Rightarrow 2x+y=72....(ii)\\\\\text{Now solve these two equation together we get}\\\\2x+(42-x)=72\\\\2x+42-x=72\\\\x=72-42=30\\ [/tex]
Hence Number of cows=30
