Answer:
n_glass = 1.404
Step-by-step explanation:
In order to calculate the index of refraction of the light you use the Snell's law, which is given by the following formula:
(1)
n1: index of refraction of vacuum = 1.00
θ1: angle of the incident light respect to normal of the surface = 38.0°
n2: index of refraction of glass = ?
θ2: angle of the refracted light in the glass respect to normal = 26.0°
You solve the equation (1) for n2 and replace the values of all parameters:

The index of refraction of the glass is 1.404