Question

The farm animals have been sorted into cows and chickens. The number of chickens is two less than five times the number of cows. The animals are 80% chickens. How many cows are there?

a. 1
b. 2
c. 3
d. 4

Answer 1

b. 2

Explanation:

Answer 2

Answer: Option b

`x=2`

Explanation:

Let's call x the number of cows and call y the number of chickens. Then we know that:

The number of chickens is two less than five times the number of cows. This means that:

`y = 5x-2`

We also know that:

The animals are 80% chickens.

This means that:

`y = 0.8 (x + y)`

`y = 0.8x + 0.8y`

`0.2y = 0.8x`

To find the number of cows we must solve the system of equations:

Replace the first equation in the second equation:

`0.2(5x-2)=0.8x`

Now solve for the variable x

`x-0.4=0.8x`

`0.2x=0.4`

`x=2`