The objective of a simple telescope has a focal length of 60 cm, and the eyepiece has a focal length of 1.5 cm. The image of an observed star will form 43.5 cm from the eyepiece. Determine the length of the tube of the telescope.

In a compound microscope, the focal length of the objective is 2 mm, and that of the ocular is 10 mm. The length of the tube that supports the lenses is 18 cm. The final image of the system is formed at 50 cm from the eyepiece. Determine:
a) The magnification of the objective and eyepiece;
b) The magnification of the microscope;