Heads and legs

There are chickens and rabbits in the yard. Together, they have 108 legs and 33 heads. How many chickens are there? How many rabbits are there?

Correct answer:

c =  12
r =  21

Step-by-step explanation:

$$\begin{gathered} 108=4r+2c \\ 33=r+c \\ r=33-c \\ 108=4(33-c)+2c \\ 108=4\cdot (33-c)+2\cdot c \\ 2c=24 \\ c=\frac{24}{2}=12 \\ c=12 \end{gathered}$$

$r=33-c=33-12=21$

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