7cos(x) + 1 = 6sec(x)
7cos(x) + 1 = 6/cos(x)
7cos^(x) + cos(x) = 6
7cos^(x) + cos(x) - 6 = 0
[7cos(x) - 6][cos(x) + 1] = 0
cos(x) = 6/7 , x = arccos(6/7) and
cos(x) = -1, x = 180
Answer:

Option A is correct.
Step-by-step explanation:
We need to find equivalent of 
First we solve 
We get 
Now checking all the options.
Option A: 
Solving 
Option B: 
Solving 
Option C: 
Solving 
Option D : 
Solving 
So, looking at the options, only Option A has the same result as given question
So, 
Option A is correct.
Do 72 divided by 6 to get 12 so the answer is D