Robbie is building a dollhouse for his niece. The living room has a width of 8 inches and a length of 10 inches, and has an area of 80 square inches. He wants to increase the width of the living room but leave the length the same. The table below shows how the area, y, changes as the width, x, changes. Part A
Determine whether this relationship is proportional or non-proportional. Justify your answer.

Part B
Find the constant of proportionality, k, for this relationship. Explain the steps that you took to find the constant of proportionality.

You may use terms from the word bank to assist you when justifying your answers and/or explaining your steps.
Word Bank: constant of proportionality, proportional, non-proportional, origin,
ratio, simplify, numerator, denominator