Here are the equations and then you solve for X
a. 2x + 42 + x - 24 = 180 
Combine like terms you get 
3x + 18 = 180 
Now 3x = 162
X = 54
Same side interior angles
b. X+ 64 = 3x - 28 
64 = 2x - 28
92 = 2x 
X = 47
Alternate exterior angles 
C. 
6x + 5x + 15 = 180
11x + 15 = 180
11x = 165
X = 15