I am working on a B.F Goodrich and Rabobank case study. I need to determine how small the combination of F and X (discount and annual fee) needs to be to make this an attractive deal. I have the discount rate needing to be above .325% to be attractive for Rabobank, and the annual fee at 8bp to make this an attractive swap for Morgan Guaranty. What type of formula set up should I be using to determine how small the combination of these two needs to be and what other information do I need to complete that formula?