One of the most difficult types of arithmetic word problems in primary school is compare problems. Among these problems, the most problematic are those in which the relational term is not consistent with the arithmetic operation required for the solution. This study investigates how 10-11-year-old primary school pupils' read and interpret compare word problems. The consistency effect and the differences between successful and unsuccessful problem solvers are mainly studied using eye-tracking technology. The results show that students are more successful in solving consistent language (CL) problems than inconsistent language (IL) problems. Regarding eye movements during reading and solving the problems, fixation duration on the relational sentence and numbers is longer in the case of IL problems than in the case of CL problems. Compared to successful problem solvers, unsuccessful solvers fixate longer on the relational term, the pronominal reference word, and the statement and relational sentence of IL problems, but not on numbers.