Man lives = 23 not live = 13 Wife lives = 35 not live = 25
P(at least one lives to 80 years) = P(man lives to 80 not woman) + P(woman lives to 80 and not man) + P(both live to 80)
P=(23×25)+(25×13)+(23×35) = 415+315+615 = 1315