Pregunta de Matemática e suas Tecnologias #01a0e94a

A confectioner sells and delivers 100 g portions of party sweets in her neighborhood. Currently, the single delivery fee is R$10.00,andthepricechargedforoneportionisR$ 25.00. Due to a sales strategy, starting next week, the single delivery fee will be R$ 15.00, and a new price will be charged per portion, such that the total amount paid by a customer purchasing 5 portions remains the same.

Starting next week, what will be the new price charged, in reais, for one portion?