The area of a rectangle is 18 square inches. The length of the rectangle is twice its width. Find the width of the rectangle (in inches).

Let the width = X

Then the length would be 2X (twice the width).

Area is Length x width, so you have X * 2X = 18

x * 2x = 2x^2

Now you have 2x^2 = 18

Divide both sides by 2:

x^2 = 9

Take the square root of both sides:

x = sqrt (9)

x = 3

The width is 3 inches.