A trapezium of area 140 m has parallel sides 10cm apart and one of these sides is 16 cm long find the length of the other parallel sides?

The area of the trapezium cannot be 140 metres since the latter is a length, not an area. Suppose the area is 140 m2 = 1400000 cm2

Suppose the length of the second parallel side is x cm.

Area of trapezium = 1/2*(sum of lengths of parallel sides*distance between them)

ie 1400000 = 1/2*[(16+x)*10]

280000 = 16+x so x = 279984 cm = 2.79984 kilometres.