The function f(x) is graphed below.

There is the point  (1, 7)  , so  f(1)  =  7

There is the point  (7, 9)  , so  f(7)  =  9

f( f(1) )  =  f( 7 )  =  9          Continuing this...

f( f(2) )  =  f( 4 )  =  8

f( f(3) )  =  f( 1 )  =  7

f( f(4) )  =  f( 8 )  =  6

f( f(5) )  =  f( 5 )  =  5

f( f(6) )  =  f( 2 )  =  4

f( f(7) )  =  f( 9 )  =  3

f( f(8) )  =  f( 6 )  =  2

f( f(9) )  =  f( 3 )  =  1

9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1   =   45

waiting for moderation of picture, then ill answer

hmm what is the equation of f(x)

hmmmm thats tricky...the equation to make those dots is needed to find the solution you ask for

is there any extra details you can give?

I'm sorry, but I don't understand this problem. If there was some more information, like what the function for f(x) was, I could solve it. ;-;