I am including a diagram. I hope I am interpreting correctly.

We can use the horizontal and vertical component formulas.

horizontal:

vertical:

When the rock is level with the point it was thrown, then it's the point where y equals 0, we can find x at that time.

Solving for t we find t=2.04 seconds to reach that point.

That means it's x coordinate is

The stone is at (35.35,0) at 2.04 seconds.

Now, we have a triangle with angle 45 and side 35.35

So, the y component is the same, y=-35.35 feet

Plug this into the y component and solve for t.

And we find

**t=3.89 seconds**
Perhaps TopsQuark will check me out.