Previous research examining comparison relations in word problems primarily focused on students' achievements in word problems with one operation. In this paper, we extend previous research to examine the achievement of students of different ages on word problems that integrate compare and combine word problems, hereafter referred to as 'compare-combine problems'. The convenience sample in this research consists of 96 second-grade, 103 fourth-grade, and 85 sixth-grade students from Belgrade, Serbia. The results indicate that 2nd, 4th and 6th graders have similar achievement on consistent language problems, but students in higher grades perform better on inconsistent language problems. We identified a type of problem that does not provide insight into students' understanding -- problem in which the order of quantities follows the order of steps in problem solving. We emphasize the importance of using integrated problems of different structures in teaching, as well as in-depth work on understanding relational terminology.