Question

state the amplitude, period and phase shift of the function y=tan (20-80 degrees)

Answer 1

The function should read y = tan(2 theta - 180 degrees).

Answer 2

write it as
y = tan 2(Ø - 90°)

We don't speak of "amplitude" with tanØ (look at a graph of sinØ )
the period of tan kØ is 180/k°
in your case the period is 180/2 = 90°
the phase shift is 90° to the right.