Answer:
We do not know how much the boat costs but suppose that the coast of the boat is X.
We know that the family takes the boat once in each season, and we have 4 seasons in the year.
So in a year, the family spends 4*X
now, if 4*X is more than $100, then the family spends:
4*X - $100 more than $100.
if 4*X is less than $100, then the change that the family receives is:
$100 - 4*X