If abc = def, then angle
a. sas congruence
b. sss congruence
c. cpctc

Hey there! :D

If you already know that two triangles are congruent, (which is given)

then any other part of the triangle can be proved congruent by CPCTC.

Congruent Parts of Corresponding Triangles are Congruent.

I hope this helps!
~kaikers

The answer is 1 because you have to flip the sign when dividing by negative number and 3