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
Two different students solved the problem
$$1\frac9{10}+5\frac4{10}$$
below. Study their work and determine whether the strategy they used works.
|                          **             Student A            **                          |                          **             Student B            **                          |
|------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------|
| .. image:: https://d21royfkw9g4l6.cloudfront.net/uploads/2022/03/24/g4mathu5l14_at1a.png | .. image:: https://d21royfkw9g4l6.cloudfront.net/uploads/2022/03/24/g4mathu5l14_at1b.png |
Problem 2
Two different students solved the problem
$$4\frac38-3\frac68$$
below. Study their work and determine whether the strategy they used works.
|                           **            Student C           **                           |                           **            Student D           **                           |
|------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------|
| .. image:: https://d21royfkw9g4l6.cloudfront.net/uploads/2022/03/24/g4mathu5l14_at2a.png | .. image:: https://d21royfkw9g4l6.cloudfront.net/uploads/2022/03/24/g4mathu5l14_at2b.png |
Problem 3
Solve.
| $$1+\frac{5}{12}$$                          $$\frac{11}{12} + \frac5{12}$$ | $$8+4\frac36$$                          $$7\frac56+4\frac36$$ | $$1\frac1{10}-\frac1{10}$$                          $$1\frac1{10}-\frac2{10}$$                          $$1\frac1{10}-\frac4{10}$$ | $$6\frac15-5$$                          $$6\frac15-4\frac45$$                          $$6\frac15-4\frac25$$ |
|----------------------------------------------------------------------------|---------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------|


aligns: no