Finding the sinusoidal input voltage of an amplifier
The greatest possible amplitude of an undistorted output sine is:

min(|L+|, |L−|) = 8 V


And the amplitude of the corresponding input sine is therefore:

min(|L+|, |L−|) ∕ 100 V/V = 8 V ∕ 100 V/V = 0.08 V = 80 mV


The minimum (min) value of the absolute values of the supply rail voltages needs to be taken in order not to exceed the supply range and so to avoid clipping: