An object is placed 30cm in front of a thin convex lens kept in air. The lens has a focal length of 12cm. Answer the following questions, showing all working steps.
a. (a) Calculate the position of the image formed by the lens.
b. (b) Determine the linear magnification produced.
c. (c) State whether the image is real or virtual, and whether it is erect or inverted. Justify your answer on the basis of the signs obtained in parts (a) and (b).