Solving for 3 variables in projectile motion problem

[babacanoosh]

Homework Statement

A dart is thrown at a 30 degree angle above the horizontal from a height of 1.6 meters. It hits the ground 20 meters away.

a) find the initial speed?
b)what is the maximum height reached by the dart (relation to the ground)?
c)what is the speed of the dart as it hits the ground?

Homework Equations

y= y1 + Vy1t - 9.8t^2
Vy = Vy1^2 - 2(9.8)(y - y1)
Vy= Vy1 - 9.8t

The Attempt at a Solution

x1 = 20
x=0
t=?
a=-9.8
y1=?
y=?


I understand that I most likely need to use the following three equations in order to isolate one variable. I am not sure which variable/how to.

 

[CompuChip]

Do you know what y1 (physically) means? Because its value is given in the problem.
So is that of y.

If you call the initial speed v, then you can rewrite v in terms of v_x and v_y and the angle (30 degrees).