26.
$$2{\log _{10}}^5 + $$  $${\log _{10}}8 \,- $$  $$\frac{1}{2}{\log _{10}}4$$   = ?

27.
If $${\log _a}\left( {ab} \right) = x{\text{,}}\,$$   then $${\log _b}\left( {ab} \right)$$   is -

28.
If $${\log _{10}}2 = a$$  and $${\log _{10}}3 = b,$$   then $${\log _5}12$$ = ?

29.
If $${\log _{10}}125 + {\log _{10}}8 = x,$$     then x is equal to -

30.
If $${\log _5}\left( {{x^2} + x} \right) - $$   $${\log _5}\left( {x + 1} \right)$$   = 2, then the value of x is -