At a school dance, tickets are sold at the door and each ticket is the same price. The amount of money the school makes from the dance is equal to the total amount of money collected from ticket sales minus the total cost of the DJ and decorations. For this dance, the total cost is fixed and is not dependent on the number of tickets sold. If 75 tickets are sold, the school loses $150. If 100 tickets are sold, the school makes $100. What is the total cost of the DJ and decorations?