An artist wants to construct a rectangular wall from square tiles. the wall is 72 inches long & 42 inches wide. All sqare tiles must be the same size & length of the sides of the tiles must be a whole # . Find 3 different square tiles that could be used to completely fill the rectangular space with no tile overlapping the border. Determine the smallest # of square tiles that could be used to fill the rectangualr space.

I am confused. the problems states to find three different sizes of square tiles that could be used to completely fill the rectangular space, with no tiles overlapping the border. Determine the smallest number of suare tiles that could be used to fill the rectangular space. I am assuming the the 3 different sizes should be used separately & not together. Thank you so much for your help