The activities director of the Community Center is planning a skating event for all the students at the local middle school. There are several skating rinks in the area, but the director does not know which one to use. At a previous event at Skate Park the director initially paid $230 for a party of 10, but when 20 students attended she ended up paying $260. For a different event at Roller Rama, she paid $125 for 25 students, but ended up paying $200 when 40 students attended.