Person 1 can do a certain job in twenty-one minutes, and person 2 can do the same job in twenty-eight minutes. When
completing the job together, which expression would be used to represent the amount of work done by person 1?

astronomers is your final answer! : )

answer: c.  

step-by-step explanation:

mixtures containing substances that get attracted to magnet can be separated using a magnet. we can separate iron from a mixture of sand and iron, as only iron attracts to the magnet.