A football is thrown horizontally with an initial velocity of (16.5 m/s). Ignoring air resistance, the average acceleration of the football over any period of time is (-9.81 m/s2). Find the magnitude and direction of the velocity at this time and direction (as an angle) below the horizon .

I am not going to do this for you. The horizontal velocity is constant, the vertical velocity increases due to gravity. The final velocity is a resultant of the horizontal and vertical.

I will be happy to critique your work.