Choose either the sss postulate or the sas postulate and explain in your own words how you use that postulate to prove two triangle are congruent.

Let's use the SAS postulate! SAS means Side, Angle, Side. I would sometimes write this the other way and get in trouble, haha. 
It technically means if a triangle that has a congruent angle between two congruent sides, it means it is congruent. Here is a picture. 

Bc equals mb that should be your answer