standard_description: Identify when two expressions are equivalent (i.e., when the two expressions name the same number regardless of which value is substituted into them). For example, the expressions y + y + y and 3y are equivalent because they name the same number regardless of which number y stands for.
problem_activity: In science class, you measure the mass and volume of different pieces of aluminum. You determine that there is a proportional relationship between mass and volume. The data on four samples of aluminum is shown in the table.
| **           Volume (cm                       $$^3$$                      )          ** | **           Mass (g)          ** |
|-----------------------------------------------------------------------------------------|-----------------------------------|
|                                            4                                            |               10.8                |
|                                            7                                            |               18.9                |
|                                           12                                            |               32.4                |
|                                           18                                            |               48.6                |
After you put your scale away, you realize that you forgot to find the mass of one more piece of aluminum. The volume of the piece of aluminum is 10 cm
$${^3}$$
. Can you determine the mass without taking your scale back out?


aligns: no