A telescope has an object whose focal length is 60cm.

(a)The telescope is used to watch a young zebra 500m away.If the image of the zebra is 20mm long and is located 25cm infront of the eye piece,find the actual length of the zebra

I am pretty sure that you have incorrectly typed "object" where you should have typed "objective" (lens or mirror.)

The distance x from objective to first image (formed by the objective) is given by

1/500 + 1/x = 1/f = 1/0.6
1/x = 1.665
x = 0.6007 m
Magnification = x/500 = 1.201*10^-3
(i.e, it is smaller than the actual zebra)

Zebra length = 0.020 m/1.201*10^-3
= 1.665 m

The information about the image distance from the eyepiece was not needed.