Common Core Alignment: Subtracting Mixed Numbers: Different Denominators

4.NF.3c:

Number And Operations - Fractions

Build Fractions From Unit Fractions By Applying And Extending Previous Understandings Of Operations On Whole Numbers.

Add and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction.

5.NF.1:

Number And Operations - Fractions

Use Equivalent Fractions As A Strategy To Add And Subtract Fractions.

Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators. For example, 2/3 + 5/4 = 8/12 + 15/12 = 23/12. (In general, a/b + c/d = (ad + bc)/bd.)