What will be the new origin after three rotations around different origins?

Question

Question: Write down the origin of the composition of three rotations:

1. Rotation by $45^\circ$ around $O_{1}$
2. Rotation by $-60^\circ$ around $O_{2}$
3. Rotation by $30^\circ$ around $O_{3}$

And write down the image of a triangle $ABC$ after each of these transformations.

I don't even know how to start.