math
posted by jack .
a square kitchen floor can be exactly covered withe square tiles that are either 9 inches or 15 inches on a side. what is the minimym area in square feet that the kitchen can have? how many of each size tile would be needed to cover the minimum size floor?

minimum area for square is either 9*9= 81 or 15*15=225. 81 is less so 81 sq. inches
each tile has a side length of 9 inches and you'd have a box of nine rows and nine columns of tiles like this
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__
so each end has nine tiles * 9 inches per tile, so that's 81 inches of tile on each side, 4 sides total so you get 81 times 4 is equal to 324 in of tile (perimeter) 
thank you mary