Please help with the following questions

3 (a) A beam of light in air is incident on the surface of a glass slab. In the air the beam makes an angle of 39 with the normal to the surface, while in the glass it makes an angle of 24 with the normal. What is the index of refraction of the glass? 3 Marks (b ) A pin 3cm long is placed in an upright position 30cm in front of a concave spherical mirror whose focal length is of magnitude 40cm. Find the location, size and nature of the image. 7 Marks