An object is projeced with a velocity of $20\;m/s$ making an angle of $45^{\circ}$ with horizontal. The equation for the trajectory is $"h = Ax - Bx^2"$ where $'h'$ is height, $'x'$ is horizontal distance A and B are constats. The ratio $A : B$ is : $(g = 10\;m/s^2)$