Ratios and Similar Polygons Help!?

that would be 18. Because the ratio of each side is 2:3, that means that ratio of the whole polygon is 2:3. so, just find a common multiple. in this case, 9. since you know one polygon is 27, and the ratio is 2:3, and 9 goes into 27 three times, that means that it must be 18 because 9 goes into 18 two times.