3. The length of a rectangle is twice that of its width. If the area of the rectangle is 72 square inches, then find the length and width.

Answer 1

Rectangle = 4 sides, with 2 sides equal to X and 2 sides equal to Y, where Y and X can be the same value (ie square)

Perimeter of rectangle = 2X+2Y

Step 1: 72ft = 2X + 2Y

The length is twice its width

Let X be length and Y be width

Step 2: X = 2Y

Step 3: 72ft = 2(2Y) +2Y

Step 4: 72ft = 4Y+2Y

Step 5: 72ft =6Y

Solve Step 5 for Y, then insert answer into Y in Step 2 and solve for X.

An example worked all the way through:

Step 1: 60ft = 2X + 2Y

Step 2: X = 2Y

Step 3: 60ft = 2(2Y) +2Y

Step 4: 60ft = 4Y+2Y

Step 5: 60ft =6Y

Step 5a: 10=Y

Step 2a: X=2(10)

Step2b: X=20

Check:

_______20____

|____________| 10

|____________|

^10 20

40+20=60