I'm not sure what AAS, SAS, SSS, ASA mean .how do I solve this?

AAS is an acronym for Angle-Angle-Side. It basically means that if two angles and a nonincluded side of one triangle are congruent to two  angles and the corresponding nonincluded side of a second triangle, then  the two triangles are congruent. SAS is an acronym for Side-Angle-Side. It means that if two sides and the included angle of one triangle are congruent to two  sides and the included angle of a second triangle, then the two triangles  are congruent. SSS is an acronym for Side-Side-Side. It means that if three sides of one triangle are congruent to three sides of a second  triangle, then the two triangles are congruent. ASA is an acronym for Angle-Side-Angle. It means that if two angles and the included side of one triangle are congruent to two  angles and the included side of a second triangle, then the two triangles  are congruent.

In the problem, we know that the corresponding sides of both triangles are congruent to each other, so those would be given. The third side of each triangle would also be congruent because of reflexive property. Reflexive property means that the two triangles share a line segment. So, the answer would be SSS.