what is the formula to find the perimeter of a rectangle: the length is twice it's width and the area is 200 ft sq.
"The formula" is what you need to come up with!
Since length is defined in terms of width, pick a variable for the width. Then translate
the relationship of "the length is twice the width" into a mathematical expression.
Take the geometrical formula
for the area "A" of a rectangle with width "w" and length "L", and plug your variable, your expression, and the given value for A into this formula.
for the width. Back-solve for the length. Then plug these values into the formula for the perimeter P of a rectangle with width w and length L.
If you get stuck, please reply showing how far you have gotten. Thank you!