Let the other parallel side be x m

The given Information is as follows:

Distance between two parallel sides = 15 m

Area of trapezium = 480 m^2

Now, we know that the Area of the Trapezium = 1/2 × (Sum Of Parallel Sides of Trapezium) × (Distance between Parallel Sides of Trapezium)

480 = 1/2 × (20 + x) × 15

Thus, (480 × 2)/15 = 20 + x

960/15 = 20 + x

Therefore, x = 64-20 = 44 m

Hence, the length of the other parallel side is 44 m