He is following the Deductive Reasoning. In simple words, Deductive Reasoning is the process of reasoning or thinking from one or more characteristics of someone or something to reach at a conclusion about them.
Like in this example, Everyday Fresh company sells its products at a discounted price, so it is very logical to think for someone that if the company opens up its new product base, that would also be at the discounted price.
So when Jason bought a set of pencils and eraser of Everyday Fresh company, he thinks that this would also be given on a discounted rate. This logical thinking is called as Deductive Reasoning.