answer a,b, and c please

15. Drug pharmacokinetics A patient takes 200mg of a drug at the same time every day. Just before each tablet is taken, 10% of the drug remains in the body. (a) If Qn is the quantity of the drug in the body just after the nth tablet is taken, write a difference equation expressing Qn+1 in terms of Qn. (b) Find the equilibria of the equation in part (a). (c) Draw a cobwebbing diagram for the equation