Interpret equations as statements that two expressions are equal, using balance models and equivalent operations on both sides to represent one-variable relationships with integers and rational numbers. Represent one-variable inequalities on number lines with open or closed endpoints and shading for the full solution range, including positive and negative fractions and decimals, and reverse the inequality symbol when multiplying or dividing by a negative. Write and solve one-step and straightforward two-step linear equations and inequalities from contexts using inverse operations, then verify equation solutions by substitution and interpret results in context.