HPLC Separation and Resolution

In a reverse-phase HPLC analysis, two compounds A and B have retention times of 12.5 min and 14.2 min respectively, with peak widths at base of 1.1 min and 1.3 min. The column dead time is 2.0 min. (a) Calculate the resolution (Rs) between peaks A and B. (b) Calculate the selectivity factor (α). (c) Calculate the retention factor (k') for each compound. (d) If you need Rs ≥ 1.5 for baseline separation, what changes would you make to the mobile phase?