1. The problem statement, all variables and given/known data Determine the behavior of a drug in the bloodstream that enters the brain and the amount of this drug in the bloodstream that is delivered to the body at a given time as it decays. The amount of drug in the body is eliminated as described by an exponential decay half life equation. Plot the behavior to show an graphical representation. 2. Relevant equations A = Ai*e^((-log(2)*(t/H)) Amount of drug in body, t is only variable dA/dt = (-log(2)/H)*Ai*e^((-log(2)*(t/H)) t is only variable dB/dt = -k1*B + (k2*A) B is amount of drug in bloodstream H = Ci*(280-W)/26 Half life Equation k1 = 2.5 Half life constant k2 = 2.7 Half life constant 3. The attempt at a solution I know what the final graph is suppose to look like where the amount of drug in the bloodstream is represented by starting at an initial value and exponentially decaying. The amount of drug in the body starts at zero and exponentially increases as the drug from bloodstream enters the body until it reaches a maximum value and then decays. Logically thinking through the problem, I would think that the amount of drug in body that decays is determined by two different decaying rates from body and bloodstream where so far I have created the equation g(t) = A(o)*(e^((-log10(2)*(t/H))) - e^((-k1*t))) but am not sure if this is correct and not sure what to plot for the amount of drug in the bloodstream. I have tried plotting this equation against A but they end up both decaying to the same value whereas the decay for the bloodstream should produce values that are a little smaller after the intersection of the graphs takes place. I did try solving for B and got B = (k2*A)/k1 + exp(-k2*t) but when I tried plotting this equation it wasn't the correct behavior. Does this have to do something with the two differential equations being coupled so I would solve for B in a different way then using integrating factors?