The perimeter of the rectangle is 34 dm. Find the length of the rectangle if its width is 500 mm.

Decision:
The perimeter of a rectangle is equal to the sum of the lengths of all its sides, that is, it is equal to: length + length + width + width. We know the width and perimeter of the rectangle, so we can find the length:
Rectangle length = (perimeter – width * 2): 2
SI: 500mm = 5dm
Rectangle length = (34-5 * 2): 2 = (34-10): 2 = 24: 2 = 12dm
Answer: the length of the rectangle is 12dm