Answer:
We know that,
The ratio between voltages in the coils is the same as the ratio of number of turns in the coil
Equation: (Vp / Vs) = (Np / Ns)
Ns, Np = no.of turns on secondary and primary coils respectively
Vs, Vp = no.of turns on secondary and primary voltages respectively
(Vp / Vs) = (Np / Ns)
Vp / 75 = (300 / 600)
Vp = 37.5 Volts
input voltage is 37.5 volts.