One side of the parallelogram is 20 cm, and the other is 5 cm larger. Calculate the perimeter of the parallelogram.

A parallelogram is a quadrangle whose opposite sides are equal.
Let a parallelogram ABCD be given, then AB = CD and BC = AD.
By the condition AB = CD = 20 cm.Then BC = AD = AB + 5 cm = CD + 5 cm = 20 cm + 5 cm = 25 cm (since it is 5 cm more).
The perimeter of a polygon is the sum of the lengths of all its sides.
The perimeter of the parallelogram ABCD is:
P = AB + BC + CD + AD;
P = 20 + 25 + 20 + 25;
P = 2 * 20 + 2 * 25;
P = 2 * (20 + 25);
P = 2 * 45;
P = 90 (cm).
Answer: The perimeter of parallelogram ABCD is 90 cm.