The answer is the first one
Since it has a half life of 60 days, this means that every 60 days it multiplies by 0.5. Since it asks for 300 days, your equation is 500*(0.5)^5, which is 15.625 mg left after 300 days.
Y = ln {[sin(x)]^2}
use the chain rule
y' = 1 /[sin(x)]^2 * 2sin(x)*cos(x) = 2cos(x) / sin(x) = 2 cot(x)
Answer: 2 cot(x)
