In order to solve mathematical problems, students often need to make the transition from one representation of mathematical concepts in those problem formulations to another representation. In this paper we explore the influence of the representations used in the problem formulation (problems with the same mathematical background with regards to solving easier or more complex equations and determining the unknown value of the proportion) on students' success in solving those problems. On a representative sample of 584 8th grade students, we tested whether there were differences in students' success in solving mathematical problems while using symbolic, graphic, or verbal representations in the formulations of problems belonging to different level of complexity. Results of this research indicate that there is significant impact of the representations of mathematical concepts used in problem formulation on students' success. Furthermore, the level of impact of using different representations in problem formulations depends on the level of the problem complexity when it comes to students' success in solving those problems.