To make this transformation using the rule T(3, -1), we need to add 3 units in the x-axis to each point, and also subtract one unit to each coordinate in the y-axis. Then, we have:
Point A (2, 1):
A (2, 1), T(3, -1) ---> A' (2+ 3, 1 - 1) =A'(5, 0).
Point B (-1, 0):
B (-1, 0), T(3, -1) ---> B' (-1 + 3, 0 - 1) = B' (2, -1).
Point C (3, 4):
C (3, 4), T(3, -1) ---> C' (3 + 3, 4 - 1) = C' (6, 3).
Then, the coordinates of triangle A'B'C' after the transformation is:
A'(5, 0), B'(2, -1), C' (6, 3).