This sample question measures eighth-graders' understanding of algebra.

The percentages below indicate how students performed on the question. In addition to the overall percentage of students who answered the question correctly, the percentage of students at each achievement level who answered the question correctly is presented.

As an example of how to interpret these percentages, 54 percent of the students overall answered this question correctly. When only the students in the *Proficient* category are considered, 86 percent answered correctly.

See more about this question in the NAEP Questions Tool.

View this question, at score 301, on a map of NAEP mathematics items.

SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2007 Mathematics Assessment.