So basically, you are looking for a base 3 log graph.
Steps:
Take the base 3 log on both sides of 3^y = 8 to get y = base 3 log 8.
To find the curve that is base three log 8, you should look at some points; in this case, the base 3 log 9=2, and base 3 log 3=1.
So, you should get a graph with points (1,0) (3,1) (9,2).
Therefore, based from what we got, the graph of function f of x equals log base 3 of x is the logarithmic graph that can be used to approximate the value of y in the equation 3y = 8.