standard_description: Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.
problem_activity: Problem 1
A repair technician replaces cracked screens on phones. He can replace 5 screens in 3 hours.
a.   Write an equation you can use to determine how long it takes to replace any number of screens.
b.   Write an equation you can use to determine how many screens can be replaced in a certain number of hours.
c.   Use one of your equations to determine how long it would take to replace 30 screens.
d.   Use one of your equations to determine how many screens could be replaced in 12 hours.
Problem 2
A train traveling from Boston to New York moves at a constant speed. The train covers 260 miles in 3.25 hours.
Write an equation that represents this relationship. Explain what your equation tells you about the train.
Problem 3
Deli turkey meat is on sale at two different grocery stores, as represented below.
| **             Stop & Buy            **              $$c=6.25p$$                        , where                         $$c$$                        represents cost in dollars and                         $$p$$                        represents number of pounds of turkey |                        **             Roger's            **                         | **                 Amount                **  **                 (pounds)                ** | **                 Cost                **  **                 ($)                ** | 3 | 19.50 | 4 | 26.00 | 6 | 39.00 | 7 | 45.50 |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------|---|-------|---|-------|---|-------|---|-------|
|                                                                                           **                 Amount                **  **                 (pounds)                **                                                                                           | **                 Cost                **  **                 ($)                ** |                                                                                            |                                                                                     |   |       |   |       |   |       |   |       |
|                                                                                                                                       3                                                                                                                                        |                                        19.50                                        |                                                                                            |                                                                                     |   |       |   |       |   |       |   |       |
|                                                                                                                                       4                                                                                                                                        |                                        26.00                                        |                                                                                            |                                                                                     |   |       |   |       |   |       |   |       |
|                                                                                                                                       6                                                                                                                                        |                                        39.00                                        |                                                                                            |                                                                                     |   |       |   |       |   |       |   |       |
|                                                                                                                                       7                                                                                                                                        |                                        45.50                                        |                                                                                            |                                                                                     |   |       |   |       |   |       |   |       |
What is the unit price of turkey per pound at each store? Which store has the better sale?


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