The roof of an apartment building is rectangular and its length is 4 times longer than its width. If the area of the roof is 900 feet squared, what is the difference between the length and the width of the roof? Choose one:  A) 38.  B) 40.  C) 42.  D) 45.  E) 46.
Answer is D : 45   Let w be the width , so length is 4w. Therefore : w*4w = 900, solving for, w = 15 , so 4w-w = 3w = 3*15= 
<gadget id="calculator">3*15</gadget>
<output>45</output>
45
<result>D</result>
The roof of an apartment building is rectangular and its length is 4 times longer than its width. If the area of the roof is 900 feet squared, what is the difference between the length and the width of the roof?