From the ideal gas law equation we know that,
From Problem 2.13 we know that,
From (1) and (2) we have,
In (4), h-h0 represents height above sea level and P0 the atmospheric pressure at sea level and T I am guessing is assumed to be 273K.
So at a height of 5 Km above sea level we have,
Similarly at a height of 5 Km below sea level we have,