It's given in the question,
Therefore, 'R' red tiles will be surrounded by the blue tiles = R × 12
= 12R
Expression used to find the number of blue tiles 'B' will be,
B = 12R
If R = 15,
Number of blue tiles used to surround 15 red tiles = 12 × 15
= 180
Therefore, total number of blue tile = 180.
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https://brainly.com/question/807984