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: Identify whether the following statements are true or false.
a.   A parallelogram is always a trapezoid. T / F
b.   A quadrilateral is always a parallelogram. T / F
c.   A parallelogram is always a polygon. T / F


aligns: no