need correct answer

7. A flask contains a mix of substances A and B that both decay with first order kinetics. a) The half time is 55h for A and 28h for B at 25C. If the initial concentrations of A and B are identical, how long does it take until the concentration of A is four times larger than that of B ? b) The activation energy for the decay reactions of A and B are 45kJ/mol and 70kJ/mol, respectively. At which temperature should the flask be kept so that the ratio [A]/[B] remains constant