Each side of rectangular polygon is 2.5cm in length. the perimeter of the polygon is 12.5cm. how many sides does the polygon have

There are 5 sides (a pentagon). The perimeter is the length of one side times the number of sides.

Regular polygon has same length for all sides.

therefore

no. of sides * length of each side = perimeter

n (2.5) = 12.5

n=12.5/2.5

n=5

therefore no. of sides = 5