Well, you can factor it. The only way I can do it is by guess and check, but you can see each term has an X in it, so factor that out first:
x ( x^2 + 3ax - 5a^2)
This does not factor evenly any further. So this could be your answer.
The fact is says "solve" confuses me too. From here you could use the quadratic formula if the equation was equal to something. But nothing was mentioned, so that's as far as I can solve for.