Kinda small but help plz

Initially 100 milligrams of a radioactive substance was present. after 6 hours the mass had decreased by 4%. if the rate of decay is proportional to the amount of the substance present at time t, find the amount remaining after 24 hours. (round your answer to one decimal place.)

Answer question above and explain each step : )

Write the expression in complete factored form. 5n_(c - 3) - n(c - 3) =