Question 600407
Let width of rectangle = X feet
So its length = 2X 

Using the formula (Length*Width) = Area, we get
2X*X = 450
i.e. {{{( 2X^2 )= (450 )}}}
i.e. {{{( X^2 )=( 450 )/2}}}
i.e. {{{( X^2 )=( 225 )}}}
so {{{X=( sqrt(225))}}}
OR X = 15

So the width of rectangle = X = 15 feet
& its length = 2X = 2*15 = 30 feet