A transformer has 500 turns in its primary coil and 4000 turns in its secondary. (a) What will be the voltage in the secondary if the primary voltage is 110? (b) If 5 amperes flow through the secondary circuit of the transformer, what will the current in the primary be? (c) If there are 8 amperes in the secondary, how many are there in the primary?

What does you text book tell you about how the ratio of windings on a transformer affect the ratio of the input and output voltages? And given that a transformer can't create energy, you know that the power going in (volts times amps) equals the power coming out.