standard_description: 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.)
problem_activity: Naja brought $20 to the corner store.
She spent $3.49 on candy.
She spent $5.79 on a Jamaican beef patty.
How much money did Naja have left?


aligns: no