Translate triangle ABC left 3, down 5 and then perform a dilation of 4 around the center at the origin.

After translating triangle ABC left 3, down 5, the coordinates become:

A (0, -3)
B (3, -3)
C (0, -1)

Performing a dilation of 4 around the center at the origin:

A (0*4, -3*4) = (0, -12)
B (3*4, -3*4) = (12, -12)
C (0*4, -1*4) = (0, -4)

So the new coordinates of the triangle after translation and dilation are:

A (0, -12)
B (12, -12)
C (0, -4)