When asked to evaluate, you have to plug in the given value of n (in this case), into the given equation.
n/6 = ? In order to find out ?, we need to know what n is. Well, n = 12 So, plug in 12 for n n/6 would now be written as 12/6 in order to be evaluated Now, simplify.... What you get for 12/6 is the answer