SOLUTION: The length of a rectangle is 15 cm longer than the width. when its width is increased by 3 cm and its length decreased by 5 cm. the area of the new rectangle is 20cm^2 bigger than

Algebra ->  Rectangles -> SOLUTION: The length of a rectangle is 15 cm longer than the width. when its width is increased by 3 cm and its length decreased by 5 cm. the area of the new rectangle is 20cm^2 bigger than       Log On


   

Question 465605: The length of a rectangle is 15 cm longer than the width. when its width is increased by 3 cm and its length decreased by 5 cm. the area of the new rectangle is 20cm^2 bigger than the original. find the original dimension of the rectangle.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

Let x and (x+15cm) represent the width and length of the 1st rectangle and

(x+3), (x+10) the width and length of the 2nd rectangle

Question states***

(x+3)(x+10) = x(x+15) + 20cm^2

Solving for x

x^2 + 13x + 30 = x^2 + 15x + 20

             10 = 2x

            x = 5cm, width of the original.  Length is 20cm.



CHECKING our Answer*** 2nd rectangle: width is 8cm and Length is 15cm

    120cm^2 = 100cm^2 + 20cm^2