When the student is not able to solve a given problem, a plausible deductive reasoning process should be offered to him/her. Our final goal is a development of an e-Learning system which could help students not too much and not too little so that they can acquire as much deductive experience of independent work as possible. In the paper, we illustrate a solution plan graph which is a plausible deductive reasoning material with a concrete word problem. Our guiding principle for conducting the deduction is the thinking method of “working backwards” from the unknown. The paper also illustrates the details of the working backwards method.