Answer question 10, and show all your work

I 10. During a biology class you are asked to study 2 different strains of bacteria. Type A began with a mass of 9g and doubles in 3 hours. Type B was treated with a disinfectant; it began with a mass of 72g and halves in 4 hours. When will the two strains of bacteria have the same mass? Justify your answer. OR