A group of 15 people goes to the cinema. Altoghether they pay 75€ for the tickets.[br]Complete the table and move the orange crosses to the right position in the coordinate system.
How much does the group have to pay if two more people join them?
Today there is a special offer called 2+1.[br]This means that if you buy two tickets, you get a third one for free.[br]How much does a group with 15 people have to pay with this special offer?
Is the special offer 2+1 a direct proportional relation?