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.   Write two equivalent expressions to represent the total area of the rectangle shown. Justify that your two expressions are equivalent.
[IMG]
b.   Expand the expression below using a rectangular array.
$${\frac{1}{3}(9x-12y-18)}$$
Problem 2
a.   What could be the missing dimensions of the rectangular array? Which set of dimensions uses the greatest common factor of the two terms?
[IMG]
b.   Factor the expression below using a rectangular array. Use the greatest common factor as the representation of the width.
$${24d-8e+6}$$
Problem 3
The table below includes expressions that are written in expanded form and in factored form. Complete the table. Use rectangular arrays as needed.
|          **           Factored Form          **          | **           Expanded Form          ** |
|----------------------------------------------------------|----------------------------------------|
|                       $$3(x-14y)$$                       |                                        |
|                                                          |               $$2x+3x$$                |
|                 $$\frac{3}{4}(8a+16b)$$                  |                                        |
|                                                          |             $$24m+8n-12p$$             |
| $$\frac{1}{2}\left(\frac{1}{3}x-8y+\frac{2}{3}z\right)$$ |                                        |
|                                                          |              $$5xy+15y$$               |
|                       $$2x(-3+y)$$                       |                                        |


aligns: no