Question

Cindy's age, x, is 3 times her age 6 years ago which equation represents the statement x=3(x-6) or x=3-6x or x=3x-6 or x=3x+6

Answer 1

x=3x+6
................

x= 9x

Answer 2

Let's denote Cindy's age which is unknown with X
We know that Cindy's age is 3 times her age 6 years ago. 
6 years ago Cindy's age was the present age (X) - 6 : X-6
The fact that the  present age is 3 times her age 6 year ago can be written as:
3*(X-6)
So, finally:
X=3*(X-6)