excel functions please

Chattanooga is considering three mutually exclusive designs for a fire station as shown in the table below. The interest rate is 12% and the project is designed to last for 70 years. Using incremental benefit-cost analysis, what is the incremental B/C ratio for the first pair when ordering the alternatives based on increasing cost? Ans. x.xx The B/C ratio for the second pair? Ans x.xx Based on this analysis, which project would you select? Ans. XXX (FS?) FS1 FS2 FS3 FS4 $8,500,000 $15,000,000 $13,500,000 $12,000,000 $2,150,000 $4,500,000 $2,225,000 $3,000,000 Investment Ann. Benefits Ann. O&M Expens. Salvage Value B/C $750,000 $825.000 $725,000 $700,000 $1,250,000 $3,265,000 1.21 1.71 $2,265,000 0.95 $2,500,000 1.40