How do I calculate N1 and N2?

We were given the following information as a task:

160MW / 50KV / 0.6 Ohm /45

With these numbers we should proceed with the same principle as in the following example.

I've managed to get through this until the last point, "Transformer" (although I'm not sure if that's all correct).

I know that N1 refers to the number of turns in the primary winding (input winding) while N2 represents the number of turns in the secondary winding (output winding).

But how do I get N1 and N2 using only these details to calculate the transformer?

Thanks in advance!