Hi guys, I'm a little stuck on this question I'm doing at the moment. If anyone has spare time, I'd be extremely grateful!

Question

A lens with 50-cm focal length produces a real image the same size as the object.

a)How far from the lens is the object?

b)How far from the lens is the image?

What I've done:
Ok...I'm looking through my textbook and the only equation that seems to fit is:
1/s+1/s'=1/f
where s: image distance in front of mirror
s': image distance behind the mirroe
f:focal length
(If my equation is wrong, just shout out! I don't care!)
But the problem is I have too many unknowns...I'm so stumped.

Anyway, just wanted to thank the incredible person who helps me in this question in advance! You da MVP!