A person has certain number of cows and birds, they have 172 eyes and 344 legs. How many cows and birds does he have?

Question

There are 12 animals in a farm.
Some are Cows
The rest are Chickens.
There are 28 animal legs in all.
How many Cows are there ?
How many Chickens are there ?

Answer 1

He have only 86 cows and dont have birds.
let suppose he have x number of cows and y number of birds. then
2x+ 2y=172 (because each have two eyes)
4x+ 2y= 344 (because cows have 4 legs and birds have 2 legs)
so x=86 and y= 0.

Answer 2

There are 86 cows only. There are 86 pairs of eyes, so there are 86 animals/birds. To make it 344 legs there should be 86 cows.