So the horizontal speed is 600cos40, and the vertical speed is 600sin40
a) Time Of Flight:
The time of flight will be the total time before it hits the floor again, so the final speed will equal the initial speed.
Using v = u + at (and taking UPWARDS as the positive direction)
-600sin40 = 600sin40 + (-10t)
t = 78.71 seconds
b) Distance Covered
We have the time it travels now, which is 78.71 seconds
Using S = ut + 1/2at^2
S = (600cos40 x 78.71) + 0 (Because the acceleration horizontal is 0, therefore 1/2at^2 is 0)
S = 36177 m
c) Max Height
This is when the final VERTICAL speed reaches 0.
Using v^2 = u^2 + 2as
0 = (600sin40)^2 + (2 x -10s)
S = 7437 m