Question

I REALLY NEED WITH THREE QUESTIONS HELP!!!! Medals!!!

Given :< 2=<4, m<2=110 degrees
Prove: <3=70 degrees
<2=<4, m<2=110 degrees given
m<2=m<4 Definition of congruent angles
m<4=110 degrees b._____________
<3 and <4 are a linear pair Definition of a linear pair
<3 and <4 are supplementary Linear Pair postulate
M<3+m<4=180 degrees c._____________
M<3-70 degree d._____

Answer 1

I know this much:
b. is substitution Property of Equality.
d. is Subtraction Property of Equality
But i dont know C.

Answer 2

@Photon336 @RainbowBrony555 @thomaster @GabeBae @imqwerty