If there are large numbers of people under 15 and over 65, what is the main challenge it creates for a...

If there are large numbers of people under 15 and over 65, what is the main challenge it creates for a country?
Economically, it's costly to provide resources to them since very little is contributed by them economically.
Economically, it's costly to provide jobs to them since very little is contributed economically.
Socially, the groups challenge a country to provide enough schools and social programs for them.
Socially, the groups challenge the people that fall between the two age groups to provide recreational programs.