2 days. Hands-on simulation activity. Used to introduce solving linear systems of 2 equations in two unknowns, with follow-up involving 3 equations and 3 unknowns. This unit studies interconversion of two drugs in the blood, that is, the case where the body metabolizes each of two drugs into the other, which is what happens for vitamin K and another chemical. This requires one day, with homework given. On the following day, you discuss solving systems of equations and can use a second set of homework that comes with this unit. The second set of homework studies drugs which are absorbed into different compartments of the body, such as vitamin A which is in the blood and in the liver. Intermediate algebra or precalculus.