Answer:
Due to the distributive property the expression are the same.
Explanation:
Sadie expression is "perimeter = 2*(length + width)", while Eric's is "perimeter = 2*length + 2*width". The value for both is always the same for any rectangle, because the expressions are the same due to the distributive property. To prove this we will expand Sadie's expression as shown below:
perimeter = 2*(length + width)
perimeter = 2*length + 2*width
Which is the same as Eric's.