First when a variable is revealed next to a number it get multiplied by it. Also the -3 needs -2 to become -5 first you have to turn the 8 into a negative so it is a negative variable. Then you need 2 which is 1/4 of 8 but, since the variable is a negative number it is -1/4.
C. The measures must be supplementary bc a line is 180º and supplementary means 180º plus the angles are vertical of each other so that means they are on the same line. I hope this helps