You are "a tad confused" :) about what's known as the
"zero-factor property"

(3n+2)(n-9) = 0

is already factored with 0 on the right side.

We have two things multiplied on the left,
they are (3n+2) and (n-9).  And when they
are multiplied on the left side of the
equation, the result is equal to the 0 on the
right side of the equation

We know that the only way that two things can
be multiplied to get 0, is for one or both of
them to be equal to zero.

So we have two possibilities, either the
first one (3n+2) equals 0 or else the second
one (n-9) equals 0, so we make two equations, 
setting each one equal to 0 separately:

(3n+2) = 0;    (n-9) = 0
  3n+2 = 0;      n-9 = 0
    3n = -2;       n = 9
     n = -2/3

So there are two solutions, -2/3 and 9

Edwin