How to find all the elements in Z(mod15) of order |b|=5

Please explain/show how to approach this problem!

Thanks!

Assuming addition as the operation, we want to find all elements b in Z_15 where
5b = 0 (mod 15).
[Since 5 is prime, no smaller positive integer n can possibly work where nb = 0 (mod 15).]

In this case, we find that b = 3, 6, 9, or 12 (mod 15).

I hope this helps!