The length of the parallel sides of a trapezium are 5cm and 7cm. If its area is 120cm(^2), find the perpendicular distance between the parallel sides

A.
5.0cm 
B.
6.9cm 
C.
10.0cm 
D.
20.0cm
Correct Answer: Option D
Explanation
Area of trapezium = (frac{1}{2} (a + b)h)
(120 = frac{1}{2} (5 + 7) times h)
(120 = 6h)
(h = 20 cm)