Medicine Erika takes 400 mg of Tylenol
for a headache. Every hour, the
amount of medicine left in her
bloodstream is divided by 2.
x=the number of hours since she
has taken the Tylenol
y = the amount of Tylenol
remaining in her bloodstream
Reasoning:

121 pints. they had 176 and drank 55

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.