There are multiple chickens and rabbits in a cage. There are 72 heads and 200 feet inside of the cage. How many chickens and rabbits are in there?

1 Answer
May 8, 2017

There are 44 chickens and 28 rabbits in the cage.

Explanation:

Since we know that both chickens and rabbits only have #1# head each and chickens have #2# legs and rabbits have #4# legs, we can set up a system of equations to solve the problem.

Let #c# be the number of chickens and #r# be the number of rabbits.
For heads, we can write the equation out in word form as:
(number of heads per chicken)(number of chickens) + (number of heads per rabbit)(number of rabbits) = (total number of heads)
In algebraic form, this equation would look like this:
#1c+1r=72# or #c+r=72#

Similarly for legs, we can write the equation out in word form as:
(number of legs per chicken)(number of chickens) + (number of legs per rabbit)(number of rabbits) = (total number of rabbits)
In algebraic form, this equation would look like this:
#2c+4r=200#

So now we have our system of equations:
#c+r=72#
#2c+4r=200#

Now we can use elimination (or substitution) to solve for c and r:
The second equation can be reduced by dividing both sides by 2:
#c+2r=100#

Here since both equations now have the coefficient of #c# as 1, we can subtract the first equation from the second equation:
#c+2r-(c+r)=100-72#
#c+2r-c-r=28# by the distributive property
By simplifying and combining like-terms, we get:
#r=28#

Now we can substitute this value of r into the first equation, #c+r=72#:
#c+28=72#
#c+28-28=72-28#
#c=44#

Therefore, there are 44 chickens and 28 rabbits in the cage.