For the first-order reaction opposed by first-order reaction:
$$A\overset { { K }_{ f } }{ \underset { { K }_{ b } }{ \rightleftharpoons } } B$$,
$${ \left[ A \right] }_{ 0 }=0.15,{ \left[ A \right] }_{ e }=0.10M,{ \left[ A \right] }_{ 10 }=0.125$$, where times are given in min.
Half-life of a reversible reaction may be defined as the time in which half of the amount of reactant which should react up to equilibrium, has been reacted. The half-life of the reaction is?