To get a side length of 12,

- the side of length 3 could be enlarged by a scale factor of 4
- the side of length 4 could be enlarged by a scale factor of 3
- the side of length 6 could be enlarged by a scale factor of 2

The perimeter of triangle A is 3 + 4 + 6 = 13, so the possible perimeters of triangle B are 52, 39 and 26.

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