CCLS - Math: 5.NF.1

Number And Operations—Fractions
Use Equivalent Fractions As A Strategy To Add And Subtract Fractions.
State Standard:
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.)