Melanie is 3 times as old as her cousin. the total of their ages is 36 years. how old is melanie's cousin?

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.)

Which of the following points is collinear with (-2,1) and (0,3)

Anyone? 15m is what percent of 60m; 3m; 30m; 1.5 km?