What I meant is 4 and 6\7 as a mixed fraction simplyfied from the improper fraction of 34\7 where the 34 is divided by 7, 4 equal times with 6\7 left over, so it 4 and 6\7

for the first part to find the mean just add all the numbers together like this:
8 + 7 + 7 + 5 + 3 + 2 + 2 = 34   then you divide that answer by the amount of terms or the amount of numbers, which is 7.   so then it would look like this:   34/7  which simplifys down to 4 6/7.

For the second problem think of f(x) to be just another way to put down a variable, "y"
so f(x) would just be y. so then for f (4) = 0 means that some function gives out the value of 0 when y = 4 and the second part f (6) = 6 means that the same function gives out a 6 when y = 6. so then you know that the function has to give out a 0 when y = 4, so then you can just put in 4 for all the x's untill one of them gives out the value of 0, in this case it is 3x - 12 where
3*4 - 12,  12 - 12, 0 , so that equation works for the value of 4. then you check it with the other part where y = 6 so 3*6 - 12,  18 - 12, which turns out a 6. so the equations works for both the values so it is the right answer.