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
32 students shared 6 pizzas equally. How much pizza will each student get?
a.   Find the exact answer.
b.   Check your work.
Problem 2
32 gallons of water is used to completely fill 6 fish tanks. If each tank holds the same amount of water, how many gallons will each tank hold?
a.   Find the exact answer. Write it as a fraction and as a mixed number.
b.   Determine which two whole numbers the answer is in between.
c.   Explain how the fractional part of the mixed number is related to the remainder in the problem.
d.   Check your work.
Problem 3
Solve the following problems. Think about the main differences between each one.
a.   A teacher has 21 batteries. Each calculator uses 4 batteries. How many calculators can the teacher fill with batteries?
b.   Four children can ride in a car. How many cars are needed to take 21 children to the museum?
c.   Ms. Cole bakes 21 cookies and wants to share them out fairly to 4 friends. How many cookies will each friend get?


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