How to find the refractive index of light if the angle of incidence and the angle of refraction are given

How to find the refractive index of light if the angle of incidence and the angle of refraction are given, for example, such a problem: the angle of incidence of light on the surface of mica is 60 degrees, the angle of refraction is 30 degrees, which is equal to the refractive index of mica.

According to the law of refraction of light, the ratio of sin of the angle of incidence 60 / to sin of the angle of refraction 30 = n is the refractive index of the second medium relative to the first.
Formula n1 * sin (angle of incidence) = n2 * sin (angle of refraction), where n1 and n2, respectively, are the absolute refractive indices of the first and second media.
The ratio of the sin of the angle of incidence / to the sin of the angle of refraction = n2 / n1 = n is the refractive index of the second medium relative to the first, in our example n2 = the refractive index of mica, but since n air = 1, then n2 / 1 = n2 = n.