Question

The length of a rectangle is 8 feet more than its width. If the width is increased by 4 feet and the length is decreased by 5 feet, the area will remain the same. Find the dimensions of the original rectangle.

Answer 1

Let the width be x.

Length is 8 feet more than width. Length = x + 8

Area = x(x + 8)

width increased by 4, that is,  (x + 4)
Length decreased by 5,    (x + 8 - 5) = (x + 3)

Area  = (x + 4)(x +3)

Area remains the same

x(x + 8) = (x+4)(x +3)

x² + 8x =   x(x +3) + 4(x +3)

 x² + 8x =   x² +3x + 4x +12

x² + 8x =   x² +7x +12        Eliminate x² from both sides

8x = 7x + 12

8x - 7x = 12

x = 12

Dimensions of original rectangle :  x,  x + 8

12, 12 +8 =   12, 20

Original rectangle is   20 feet   by 12 feet 

Answer 2

Answer:

12 feet by 20 feet

Step-by-step explanation:

Area = (x+4)(x+3)

x=12

x+8 = 12+8 = 20

Original triangle is 12feet by 20 feet