There is an animal farm where chickens and cows live. All together, there are 84 heads and 210 legs. How many chickens and cows are there on the farm?

1 Chicken have = 2 legs

1 Cow have = 4 legs

No of cows = x

No of chickens = y

Total no of legs = 4x + 2y = 210 ... (1)

Total No of heads = x + y = 84 ... (2)

x = 84 - y ... (from (2))

Substituting the above equation in (1)

4 (84 - y) + 2y = 210

336 - 4y + 2y = 210

336 - 2y = 210

-2y = - 126

= y = 63

No of cows = 84-63 = 21

∴ Total no of cows = 21

Total no of chickens = 63