36.
$$\eqalign{ & \left[ {\frac{1}{{\left( {{{\log }_a}bc} \right) + 1}} + \frac{1}{{\left( {{{\log }_b}ca} \right) + 1}} + \frac{1}{{\left( {{{\log }_c}ab} \right) + 1}}} \right] \cr & {\text{is}}\,\,{\text{equal}}\,{\text{to - }} \cr} $$

37.
$$\eqalign{ & {\text{If}}\,\,{\log _{10}}7 = a,{\text{then}}\,\,{\log _{10}}\left( {\frac{1}{{70}}} \right)\,\, \cr & {\text{is}}\,\,{\text{equal}}\,\,{\text{to}} - \cr} $$

38.
$$\eqalign{ & {\text{If}}\,\,\log x - 5\log 3 = - 2, \cr & {\text{then }}x{\text{ equals - }} \cr} $$

39.
$$\eqalign{ & {\text{If }}a = {b^2} = {c^3} = {d^4}, \cr & {\text{then}}\,{\text{the}}\,{\text{value}}\,{\text{of}}\,{\log _a}\left( {abcd} \right)\,{\text{would be - }} \cr} $$

40.
$$\eqalign{ & {\text{If}}\,{\log _3}x + {\log _{\underline 9 }}{x^2} + {\log _{27}}{x^3} = 9, \cr & {\text{then}}\,\,x\,\,{\text{equals - }} \cr} $$