we know that
AAS -----> if two pairs of corresponding angles and a pair of opposite sides are equal in both triangles.
In this problem
triangle ABC and triangle RST are congruent by AAS
because
AC=RT
that means ------> we have two pairs of corresponding angles and a pair of opposite sides that are equal
we have that
ASA -----> if any two angles and their included side are equal in both triangles.
