Can someone tell me if I'm right

I am not sure, but I think the answer is 150units

Explanation:

cause area of a trapezoid is A=1/2(a+b)h

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

the answer to your question is c