Elphaba said:
um... what's the equation and how do you get the equation
I suppose I'll just display it in easy terms.
Find the initial vertical velocity and the initial horizontal velocity.
horizontal initial velocity = cos(30) * 20 = 17
vertical initial velocity = sin(30) * 20 = 10
since 9.8 is the gravitational acceleration, the projectile should reach the top of the path at 10/9.8 seconds, which is ~1. Since the time from the bottom to the top of the parabola is equal to the time from the top to the bottom, we have to multiply this number by 2, which brings us to ~2. Now we know that t = ~2 seconds, and, so we simply multiply this number by the horizontal initial velocity and we should get the total distance (this is brought about by the equation x = (v_{ix})(\Delta t) + \frac{1}{2}a_xt^2, but since there is no horizontal acceleration, the second part of the equation drops out, leaving x = (v_{ix})(\Delta t))
As you can now see, the result is ~34 meters.
So, as for your question, there is no general equation since there are multiple parts to this problem. Instead, there are 3 or 4 that you have to use to find the final result.