A fun park is celebrating its 25th birthday and has come up with the following discount campaign: Everybody is given 50% discount on their admission ticket. Children younger than 4 years, adults…

A fun park is celebrating its 25th birthday and has come up with the following discount campaign:

Everybody is given 50% discount on their admission ticket. Children younger than 4 years, adults older than 64 years, and for this special occasion adults aged 25 years will be allowed in free. How many equivalence classes are included in this situation?