in a neighborhood the ratio of houses with swing sets to houses without swing sets is 3 to 5. if the number with swing sets is 270 how many houses do not have swing sets

When solving this problem: 3025/5.5 = a/90.75 you get 49912.5 which would be the length of one of the sides of a square when the area is only 90.75 inches. is that answer correct, why, and how is it possible?