12. Two securities have the following payoffs: State Future Prices Security S Future Prices Security T 1 2 $10 $20 $30 $10 The current prices are G(1) = $8 and H(1) = $9. Both future states are equally likely. Your initial endowment (current wealth) is $720. a. If you wanted to purchase a completely risk-free portfolio, how many units of G and H would you buy (fractional units are permitted)? b. What will be the implied risk-free return