We first have to recall the hypothesis given, that imples that the fist step to take is the one marked with number III.
Now, we notice that the vectical angles are congruent, which is step number II.
Next, we notice that the alternate interior angles are congruent, which is step number V.
Then, by the AAS criteria we have that the triangles are congruent triangles ( I ) .
Finally we the corresponding sides of corresponding triangles are equal( IV).
So the order is III, II, V, I, IV.