We suppose that T<3, -6> stands for a translation 3 units to the right and 6 units down. Adding (3, -6) to each of the coordinates gives ...
A + (3, -6) = A'(5, -11)
B + (3, -6) = B'(-1, 0)
C + (3, -6) = C'(6, -5)
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Likewise, we suppose r(90°, O) stands for rotation 90° CCW about the origin. This means coordinates (x, y) are replaced by (-y, x).
A(2, -5) ⇒ A'(5, 2)
B(-4, 6) ⇒ B'(-6, -4)
C(3, 1) ⇒ C'(-1, 3)
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We have no idea what Rx=3 means, so cannot help there. It seems possible that the x-coordinates are supposed to be multiplied by 3, which would give
A'(6, -5), B'(-12, 6), C'(9, 1)
YMMV
