Answer:
The answer is 170 feet
This is how to solve the question
When you are below sea level it means that you are at a negative (in math terms)
So you are 50 feet below sea level and you want to get to a place that is 120 feet high
So you take 50 into account because your starting below sea level then you add 120 for the distance to get up the mountain
120+50= 170
Hope that helps!