What is the midpoint between 2+8i and 2-i

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.)

Give the functions f(x) = |x + 2| - 3, what is the domain? a, b,c, or d all real numbers x > 2 x < -2 all real numbers and x cannot equal to 2

I’m really confused and need to learn this