Answer
a) 2
b) 4
c) 7
Work Step by Step
We are given
$$f(n)=f(n/3)+1$$
and $$f(1)=1$$
a) Apply the recurrence relation when $n=3$
$f(3)=f(1)+1$
$=1+1$
$=2$
b) Apply the recurrence relation when $n=27$
$f(27)=f(9)+1$
$=f(3)+2$
$=f(1)+3$
$=1+3$
$=4$
c) Apply the recurrence relation when $n=729$
$f(729)=f(243)+1$
$=f(81)+2$
$=f(27)+3$
$=f(9)+4$
$=f(3)+5$
$=f(1)+6$
$=1+6$
$=7$