Rectangle A has side lengths of 6 cm and 3.5 cm. The side lengths of rectangle B are proportional to the side lengths of rectangle A.

What could be the side lengths of rectangle B?

A. 3cm and 1.75cm

B. 5cm and 2.5cm

C. 7 cm and 7cm

D. 12cm and 5 cm

E. 5.25cm and 9cm

To determine whether or not these are proportional, take the two side lengths that are given and create a ratio. 6cm:3.5cm. I suggest writing this in fraction form to better see the equivalency. If you divide both 6cm and 3.5 cm by 2, you create an equivalent ratio of 3 cm:1.75cm. This is answer A. There is another correct answer too! If you take 6cm:3.5cm and multiple both by 1.5, it will create an equivalent ratio of 9cm:5.25 cm (answer choice E), just in a different order.