Question

Randomly selecting someone who is over 45 years or over

Answer 1

"45 years or over" includes all of the age groups "45-64", "65-74", and "75 or over". These age groups are disjoint (no individual can belong to more than one group), so the probability of picking someone that's at least of 45 years of age is the sum of the probabilities that a person belongs to any one of these groups. That would be

$24.8\%+9.6\%+6.6\%=41\%$