What is the range and equation of axis for the function : y=3sin(-2x + Pi/3) - 1

the axis for sinθ is at y=0

This is shifted down 1, so its axis is at y = -1

The range of sinθ is [-1,1]
So the range of 3sinθ is [-3,3] -- that is, the axis ± the amplitude
This is shifted down 1, so its range is [-4,2]