I need help with geometry

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.)

Ihave a triangle with a 60 degree angle. lets use d for that angle. what are the values of e and f if d is 60 degrees? and what do you notice about the values of e and f?

What should be done to both sides of the equation in order to solve -5m = -40? a) multiply by -5. b) divide by -5. c) multiply by -40. d) divide by -40.