PARAMETERS PROVIDED:
The elevations of the cities are given, all above sea level:
CALCULATIONS:
Since the elevation of City D is half of that of City C, we can calculate this as shown below:
CONCLUSION:
Part 1: The expression is shown below:
Part 2: The elevation of City D is 6 ft.
Part 3: The answer is positive. This is because City D is still above sea level since that of City C is as well. All elevations above sea level are positive.