Answer
The dimension of the flag is 20 inches x 25 inches.
Work Step by Step
Let $x$ inches by the width of the rectangular flag.
Length = $2x - 15$
Area = Length x width
$(2x - 15) \cdot x = 500$
$2x^2 - 15x - 500 = 0$
By quadratic formula, $x = \frac{-(-15) \pm \sqrt{(-15)^2 - 4 \cdot 2 \cdot (-500)}}{2 \cdot 2}$
$x = 20$ or $x = -12.5$ (rejected)
So, the width is 20 inches and the length is $2(20)-15 = 25$ inches.
The dimension of the flag is 20 inches x 25 inches.
