Number and Geometric Relations
The length of a rectangular picture frame is 5 inches (in.) less than twice its width. Its perimeter is 32 in. What are its dimensions?
Represent the length and width of the picture frame (given in inches). Let and
The length of the frame is 5 in. less than twice the width. Thus,
The perimeter of the frame is 32 in. Applying the formula for the perimeter of a rectangle, you will get
You now have a system of two linear equations in two variables.
To solve for y, substitute for x in the second equation.
To solve for x, substitute 7 for y in
Thus, the solution of the system is
The length of the frame (which is 9 in.) is 5 in. less than twice the width, which is The perimeter of the frame is
The two numbers satisfy the conditions of the given problem. Thus, the length of the picture frame is 9 in. while its width is 7 in.
