How large is the image of the Sun on film used in camera with? (a) A 28-mm-focal-length

Question:

How large is the image of the Sun on film used in camera with?
(a) A 28-mm-focal-length lens.
(b) A 50-mm-focal-length lens, and
(c) A 135-mm-focal-length lens?
(d) If the 50-mm lens is considered normal for this camera, what relative magnification does each of the other two lenses provide? The sun has diameter 1.4 x 106km, and it is 1.5 x 108 km away.