Question 14477
x=sea level
x+40=52.8
x=52.8-40
x=12.8
So the change would be 12.8, and he went up.
You have to think of a number line, the sea level is 0, and on a number line is -52.8 further away from 0 than   -40? yes
So he got closer to 0, which means he went up
=)