Coffee shops have two types of costumers. Customers who sit in the coffee shop (40%) and to-go customers (60%). The companys marketing consultant thinks that offering food will increase the sales of the existing drinks to to-go costumers by 15% (they stop by for food and they also buy a drink). However, since eating food takes a longer time and the spaces in the coffee shops are limited, offering food will lower the sales of the existing drinks to the first type of customers by 10% (some customers cant find a seat and just leave without buying anything).