It is given that ∠BOD = 40o
From the figure we know that ∠BOD and ∠AOC are vertically opposite angles
∠AOC = ∠BOD = 40o
It is given that ∠AOE = 35o
From the figure we know that ∠BOF and ∠AOE are vertically opposite angles
∠AOE = ∠BOF = 35o
From the figure we know that AOB is a straight line
So it can be written as
∠AOB = 180o
We can write it as
∠AOE + ∠EOD + ∠BOD = 180o
By substituting the values
35o + ∠EOD + 40o = 180o
On further calculation
∠EOD = 180o – 35o – 40o
By subtraction
∠EOD = 105o
From the figure we know that ∠COF and ∠EOD are vertically opposite angles
∠COF = ∠EOD = 105o