Use Bernoulli's to convert velocity to pressure.
Back pressure is given.
Use Table A-6 for air properties at different altitudes. You may also consult Table 7.3. As the ball travels on its path, it slows down due to drag, and drops due to the action of lift and gravity. The deceleration in the x-direction comes partially from Drag force and partially from the lift force. The acceleration in the y-direction comes partially from drag, partially from lift, and gravity.