Question

Miss Sullivan owns a farm where she has a total of 28 birds and dogs the total number of legs on those animals is 70 how many dogs and how many birds are on the farm

Answer 1

21 birds and 7 dogs

Explanation:

Represent Birds with B and Dogs with D

`B + D = 28` ----- Total Animals

A bird has 2 legs and a dog has 4, so:

`2B + 4D = 70` ---- Legs

Required

Solve for D and B

Make D the subject in the first equation

`D = 28 - B`

Substitute 28 - B for D in the second

`2B + 4(28 - B) = 70`

`2B + 112 - 4B = 70`

Collect Like Terms

`2B - 4B = 70 - 112`

`-2B = -42`

Solve for B

`B = -42/-2`

`B = 21`

Recall that:
`D = 28 - B`

`D = 28 - 21`

`D = 7`

Hence, there are 21 birds and 7 dogs