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: Problem 1
There are a few more ingredients in Lin’s family recipe for cookies, listed below. Write an addition equation and a multiplication equation to show how she can use the
$$\frac14$$
-cup measure to measure the amount of each ingredient below.
a.
$$\frac94$$
cups chocolate chips
b.
$$2\frac34$$
cup flour
Problem 2
Decompose each of the following fractions as a sum of unit fractions, a multiple of a unit fraction, and a sum of non-unit fractions.
a.
$${{8\over2}}$$
b.
$$3\frac{1}{4}$$
c.
$${{12\over5}}$$
Problem 3
Compose each of the following expressions.
a.
$${{1\over3}+{1\over3}+{1\over3}+{1\over3}+{1\over3}+{1\over3}}$$
b.
$${{3\over5}+{2\over5}+{6\over5}}$$
c.
$$12\times\frac{1}{4}$$
d.
$$9\times\frac{1}{2}$$


aligns: no