Answer:
21 pieces of chickens.
Step-by-step explanation:
Given:
The farmer has a total of 40 animals. ( cows and chicken )
He counts the legs of all his animals and realizes he has a total of 118 legs.
Question asked:
How many chickens does the farmer have ?
Solution:
Let number of chickens = 
Then number of cows = 
Now, as here given that total number of legs are 118 of all the animals, and as we know that a chicken has two legs and cow has four legs, hence the equation will be :
<u>Total number of legs = Number of legs having chickens + Number of legs having cows</u>


Subtracting both sides by 160

By adding both sides by minus

By dividing both sides by 2

Hence, farmer have 21 pieces of chickens.