Understand a fraction a/b with a > 1 as a sum of unit fractions (1/b).
a. Understand addition and subtraction of fractions as joining and separating parts referring to the same whole.
b. Decompose a fraction into a sum of fractions with the same denominator by recording decompositions using a variety of representations, including equations. Justify decompositions.
c. Add and subtract mixed numbers with like denominators by using properties of operations and the relationship between addition and subtraction or by replacing each mixed number with an equivalent fraction.
d. Solve word problems involving addition and subtraction of fractions referring to the same whole and having like denominators using a variety of representations.