Let's ignore the four corners for now.
Along the top, the length is 145 cm. Each tile is 25 mm, which is equivalent to 2.5 cm. So she'll need 145/2.5 = 58 tiles across the top
Similarly, she'll also need 58 tiles across the bottom as well because that length is also 145 cm.
Along the left side, she'll need 75/2.5 = 30 tiles and the right side is the same story.
So far we calculate 58+58+30+30 = 176 tiles
Add in the four corners to get 176+4 = 180 tiles total
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A quicker method is to divide the perimeter (440 cm) over the side length of each tile (2.5 cm) and we get 440/2.5 = 176, which represents the number of tiles along the top, bottom, left and right sides. Again we're ignoring the corners. So we'll have to add them back in to get 176+4 = 180.