Question

Farmer Brown has 42 animals, which are cows and chickens. They have a total of 120 legs. Write a system of equations, show your work, and solve for the number of chickens Farmer Brown has.

Answer 1

Answer:

The system of equations is:

x + y = 42

4x + 2y = 120

And there are 24 chickens.

Step-by-step explanation:

We know that the total number of cows (x) plus the total number of chickens (y) is 42, because Farmer Brown has 42 animals.

We also know that cows (x) have 4 legs and so 4 times the number of cows is the number of cow legs. And chickens (y) have 2 legs, so the number of chickens times two represents the total chicken legs. The sum of 4x + 2y is 120 because there are 120 legs in total.

To solve the system of equations, first solve each equation for y.

In the first equation:

x + y = 42

Subtract x from both sides to isolate y.

y = 42 - x

Second equation:

4x + 2y = 120

Subtract 4x from both sides

2y = 120 - 4x

Divide both sides by 2

y = 60 - 2x

Now that the y's are isolated in both equation, you can put them into 1 equation. Where y = y:

y = 42 - x

y = 60 - 2x

42 - x = 60 - 2x

Add 2x to both sides

42 + x = 60

Subtract 42 from both sides

x = 18

Since x is the number of cows, we know that Farmer Brown has 18 cows.

Now we can substitute the x value into one of the equations:

y = 42 - x

y = 42 - (18)

y = 24

The number of chickens is represented by y, so there are 24 chickens.