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: Rishi is trying to find the total number of clouds in the following array.
[IMG]
Rishi says "I know 3 × 9 = 27, so I can use that to help me solve."
a.   Mark the array above to show how Rishi is thinking about it.
b.   Use the fact that
$$3\times9=27$$
to find the total number of clouds in the array.


aligns: no