It is a math problem of first degree equations:

In a farm there are rabbits and chickens, in total 39 heads and 126 legs. How many rabbits and how many chickens are there?

Can you explain me this probles step by step?

Step-by-step explanation:

Ok, so there are rabbits and chickens

Rabbits have 4 legs and 1 head

Chickens have 2 legs and 1 head

So obviously we have a total of 39 animals

Let's make rabbits = x and chickens = y

So now we can make an equation for heads and and equation for legs.

Legs:

4x + 2y = 126

Heads:

x + y = 39

Now we can use substitution to solve.

If x + y = 39, then y = 39 - x

So,

4x + 2 (39-x) = 126

Distribute and Combine like terms

4x + 78 - 2x = 126

2x + 78 = 126

2x = 48

x = 24

Plug x back in to the second equation

(24) + y = 39

y = 15

That means,

x = rabbits = 24

y = chickens = 15