The length of a rectangle is x units and the width is x-5. How do I find an equation for the perimeter and area of the rectangle?

It should be included in the problem. If it is a right triangle, use the Pythagorean Theorem (A squared + B squared = C squared) to find the missing side.

Divide the area by the length, giving you the width. Add twice the width to twice the length.

Let x = the width. Then the length is 2x - 7. The perimeter is twice the width plus twice the length: 64 = (2x) + 2(2x - 7) =...

You also need to know the volume, in which case, you would divide the volume by the area.

The perimeter equals the side length times the number of sides. In this case, multiply 21 by 9 and you will get a perimeter of 189.

Such a rectangle would have its sides and diagonal in the ratio of 2:1:√5 (per the Pythagorean theorem). The ratio of √5 to the diagonal (20) is equal to the...

Use the Pythagorean Theorem to find the other side. Then multiply the length by the width.

Use the Pythagorean Theorem (a^2 + b^2 = c^2). A and B are the lengths of the two sides of the rectangle. To get the length of the hypotenuse, you...

Let B equal the breadth. Then 2B equals the length. Write an equation in B, stating that the perimeter is equal to twice the breadth plus twice the length. Solve...

Double the width, and subtract that from the perimeter. Then divide that number by two, which gives you the length of the rectangle. Then, multiply the result by the width...