Answer:
a) 38.27    b) 322.5°
c) 126.99   d) 1.17°
e) 62.27   e) 139.6°
Explanation:
First of all we have to convert the coordinates into rectangular coordinates, so:
a=( 43.3 , 25)
b=( -48.3 , -12.94)
c=( 35.36 , -35.36)
Now we can do the math easier (x coordinate with x coordinate, and y coordinate with y coordinate):
1.)  a+b+c=( 30.36 , -23.3) = 38.27 < 322.5°
2.)  a-b+c=( 126.96 , 2.6) = 126.99 < 1.17°
3.) Â (a+b) - (c+d)=0 Â Solving for d:
   d=(a+b) - c = ( -40.36 , 47.42) = 62.27 < 139.6°