7a) The population density is highest in the west. It is lowest in the north, east, south (and south-west).
7b) The population grows fastest in the west, because there is a lot of work and a lot of national migration there.
7c) Because the percentage of people over 65 in the population is increasing.
7d) Because there are few cities there and not a lot of work. The young people move away, which means few children are born there. The old people stay behind.