Question

Jessie has some chickens and rabbits. There are 30 heads and 76 legs in all. How many chickens and rabbits does Jessie have?

Describe what you did in attempting to solve this problem.
How do you know the solution is correct?

Answer 1

There are 22 chickens and 8 rabbits

Explanation:

1 chicken = 2 legs

1 rabbit = 4 legs

we need to do 2 equations to solve this problem

c + r = 30

c*2 + r*4 = 76

we clear c in the first equation

c + r = 30

c = 30 - r

we replace c with (30 - r) in the second equation

(30 - r) * 2 + r * 4 = 76

60 - 2r + 4r = 76

-2r + 4r = 76 - 60

2r = 16

r = 16/2

r = 8

now we replace r in the first equation

c = 30 - r

c = 30 - 8

c = 22

There are 22 chickens and 8 rabbits

Do you know that you have the correct solution because you can verify it by multiplying

22 * 2 + 8 * 4 =

44 + 32 = 76