based on the expression dp$/$dz $=-$pg at what elevation is the absolute pressure $75\%$ of the pressure at sea level. Take g to be a constant assume changes in the atmosphere's state with elevation to be polytropic with n$=1\mathrm{.}243$ and take the temperature and pressure of the atmosphere at sea level to be $10\mathrm{.}5$ degrees celsius and $1\mathrm{.}04$ atm