ok I really need help on this !

Answer:
height = 20 km
Step-by-step explanation:
Area of a trapezoid = (base + base / 2) x height
180 km^2 = (4 + 14 / 2) x height
180 km^2 = (18 / 2) x height
180 km^2 = 9 x height
height = 20 km
(fill in the numbers and work backwards)