Cooking Prime Rib

I need advice please. I am having 14 people for Christmas Dinner. I bought one 9.13 lb (4 ribs) prime rib roast and a 7.75 lb (4 ribs) prime rib roast. How long and at what temp should I cook these for medium rare. I don’t cook prime rib hardly at all and am a bit nervous. In case it matters: I have a WOLF range/oven. Thank you.

Thank you for the link but here is my question: since I have 2 roasts; one 7.75 lbs and the other 9.13 lbs do I cook per pounds based on the total weight of both roasts or just use one of the roasts to time my dinner?