The length of a rectangle is twice the width. the perimeter is 90 inches. what is the rectangle's area?
you write the equation 2w + 2w + w + w = 90 for the word problem. you solve and get 15. what is the answer to the problem?
a) the area is 450 in2.
b) the width is 15 inches.
c) the area is 112.5 in2.
d) the length is 30 inches.

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters