This is:
ha ha!

You are a Swedish family. In the ordinary Soviet family of 4 people, as a rule, there were two children, children up to 2 years old, sitting on their knees with adults, flew for free, children from 2 to 12 for 50% of the price per seat.

Only not in the summer - on vacation - at full cost.
After 12 years, life is not over.

There were no increasing and decreasing coefficients in the USSR depending on the season for the cost of tickets.