Question

What are the dimensions of the pond? Please help.

Answer 1

Let's assume

length of box is l

width of box is w

we know that

area of rectangle = length*width

`21=l*w`...................(1)

now, we are given

fencing length is 20 foot

fencing length will be equal to perimeter

and we know that

`perimeter=2(l+w)`

so, we get

`2(l+w)=20`

now, we can solve for l

`l=10-w`

now, we can plug that in first equation

`21=(10-w)*w`

now, we can solve for w

`10w-w^2=21`

`w^2-10w+21=0`

`(w-7)(w-3)=0`

`w=7 , w=3`

now, we can find length

`l=10-3=7`

or

`l=10-7=3`

so, option-B..................Answer