Answer:
Nick and Elaine can go on the boat safely
Elaine and Dario can go on the boat safely
Nick and Dario can NOT go on the boat safely
Explanation:
Nick's weight + Elaine's weight = 268, 288<310
Elaine's weight + Dario's weight = 287, 287<310
Nick's weight + Dario's weight = 315, 315>310