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: Task
To compute the perimeter of a rectangle you add the length, $l$ and width, $w$ and double this sum.
Write an expression for the perimeter of a rectangle.
Use the expression to ﬁnd the perimeter of a rectangle with length 30 and width 75.


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