Calculating speed of light in substance

[dev-hud]

A light ray initially in water enters a transparent substance at an angle of incidence of 37 degrees, and the transmitted ray is refracted at an an angle of 25 degrees. calculate the speed of light in the transparent substace.

I have my diagram drawn out, however i do not see how to solve for V (speed) using angles and what i have. I do not know which equations to use, very confuzed.

 

[nasu]

Use Snell's law. You'll find the index of refraction of the medium and then the speed of light in the medium (see definition of index of refraction).
The index of water is supposed to be known (about 1.3)