The centroid of a triangle is the point of interection of all the three medians and they have the following property:

Then, we have the following result:

By substituting the given information into this equation, we have

or equivalently,

Now, by multiplying both sides by 2x-1, we get

and by dividing both sides by 2, we obtain

We can obtain this last result if we distribute the number 2 into the parenthesis and divide the result by 2, that is,

Now, by subtracting x to both sides of the last resutl, we have

and by adding 1 to both sides, we obtain

or equivalently, x=5.
Finally, in order to obtain AN, we must substitute the last result into the expression for AN. It yields,

Therefore, the answer is: AN = 9