Rewrite log_{9/8}x as the ratio of
natural logarithms. (Keep fractions in their simplified improper fraction form)

log_{9/8}x=ln ()/ln ()

According to the Change-of-Base Formula, we can rewrite any logarithm as a ratio of common logarithms (base e).

log_{a}x=ln x/ln a

log_{9/8}x=log x/log (9/8)