Kylie is ordering a taxi from an online taxi service. She has to pay a flat charge just to order the taxi, and then has to pay per mile, depending on how far she travels. She wrote an equation to represent her total cost, y=3.5+2.3xy=3.5+2.3x, where yy represents the total cost in dollars and cents, and xx represents the number of miles she travels. What could the number 3.5 represent in the equation?