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