This is a six sided polygon. Among the six sides we know the five sides are given as variables. Let us suppose the sixth side is f. It follows f=180-x hence x=180-f
For six sided polygon total degrees inside the polygon is given by (n-2)180 = (6-2)180= 720
From this 720=a+b+c+d+e+f
or, 720-a-b-c-2c-1/2 a = f
replacing the value of d and e as mentioned in the question
Since x=180-f
x= 180-(720-a-b-c-2c-1/2 a)
rearranging the term we get x as option A
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