The distnace from a plane to a point can be found here Point-Plane Distance -- from Wolfram MathWorld

I am not sure what you plane is. You only specify one point for the plane, we need more information. If you can put the equation of the plane in standard form

and write the equaiton of the line in parametric form

If you use the reasoning or the formula in the link above you will get

Now just sub into the equation and solve for t.