Suppose a three-state single period economy with three base assets: the zero coupon bond with price St(1) = Bt, a stock with price St(2) = St, and call upon the stock with price St(3) = Ct = Ct(St,K), where t is between 0 and T. Let St(w1) = S+, St(w2) = So, and St(w3) = S- and suppose the call is struck at K=So where S- < So < S+. Set g=S as the numeraire asset price process and write down the linear system of three equations in the probabilities q(j) = P(w(j)) for j=1,2,3 corresponding to the martingale conditions for the relative base asset prices. Leave the equations expressed in terms of S+, S- So, Co, and the bond return r.