A small object is positioned 20cm from the first of a train of three lenses having focal lengths, in order, of 10, 15, and 20 cm. The first two lenses are separated through 30cm and the last two by 20cm. Compute the final position relative to the last lens and its magnification relative to the original object if (i) all the three lenses are positive and (ii) the first and last lenses are negative.