Answer:
a. from A to B, a rotation by 90 degrees anti-clockwise about (0,0).
b. from B to C, a translation by vector (-3/4, -1/4).
c. from A to C, a rotation by 60 degrees, anti-clockwise about (0,0).
Hope this helps, I'm sorry if it doesn't. If you need more help, ask me! :]