Light enters from air to glass, with glass having a refractive index of 1.50. What is the speed of light in glass? (Speed of light in a vacuum is 3 x 10⁸ m/s)

We know, 

$n_{ } = \frac{v_1}{v_2} = 1.5$ 
where n is the refractive index of glass with respect to air, $v_1$ is the speed of light in vacuum and $v_2$ is the speed of light in glass

v₂= $\frac{{\mathrm{v}}_1}{\mathrm{n}}$

$v_2$ = (3 x 10⁸) / 1.5 = 2 x 10⁸ m/s