A farmer counts his cows and chickens. If he counts 20 heads and 64 feet, how many chickens does he have?
The farmer has
We let the number of cows be
We know that each creature must only have one head, hence we derive our first equation
We also know that a cow has 4 feet while a chicken only has
Let's start by simplifying the second equation.
So, there are
Hopefully this helps!