In a basic solution how does the concentration of H3O+ compare to concentration of OH-?

Answer 1

If the solution is basic, the OH is more than the H3O^+.
(H3O^+)(OH^-) = Kw = 1E-14
Knowing either allows you to calculate the other.

Answer 2

In a basic solution, OH- is greater than H+

Answer 3

Acids are H+, or higher in concentration of H+
Bases are OH-

Acids are pH 1-6
7 is neutral
Bases are pH 8-14