Question

Susan saw birds and mice eating seeds on the ground. She counted 14 heads and 40 legs in total. How many birds and mice are on the ground?

Answer 1

8 birds and 6 mice

Explanation:

Given:

Number of heads = 14

Number of legs = 40

Required

How many birds and mice are on the ground?

Let M represents Mice and B represents Birds

Birds and Mice have 1 head each;

So;

`B + M = 14`

Birds have 2 legs; Mice have 4 legs

So;

`2B + 4M = 40`

At this point, we have two equations;

Make B the subject of formula in the first equation

`B + M = 14` becomes

`B = 14 - M`

Substitute 14 - M for B in the second equation

`2(14 - M) + 4M = 40`

Open bracket

`28 - 2M + 4M = 40`

`28 + 2M = 40`

Subtract 28 from both sides

`28 - 28 + 2M = 40 - 28`

`2M = 40 - 28`

`2M = 12`

Divide both sides by 2

`(2M)/(2) = (12)/(2)`

`M = 6`

Recall that
`B = 14 - M`

So;

`B = 14 - 6`

`B = 8`

Hence, there are 8 birds and 6 mice