First let's start with A
All the sides in a hexagon add up to 720
do 720/6
720/6=120
A=120
Each angle in that hexagon adds up to 120
Then B
The triangle is equilateral, so 180/3=60
B would be 60
C would also be 60
D is = to a, so D=120
A:120
B:60
C:60
D:120