The answer is C. Explanation is below:
All of the equations equal 6x-1 when they are simplified except for C. the work is below:
a. 6(x-1)+5 → Distribute the 6 times x and 6 times -1
6x - 6 + 5 → Now combine like terms
6x - 1
b. 6x - 1 → This is already simplified.
c. 6(1-x)+5 → Distribute the 6 times 1 and 6 times -x.
6 - 6x + 5 → Combine like terms
-6x + 11
d. 5 + 6x - 6 → Combine like terms
6x - 1