Please use the OECD database for exchange rates and PPPs:

https://stats.oecd.org/Index.aspx?DataSetCode=CPL

Applying the concept of cross rates, please evaluate how potential over-or undervaluations between Germany and Poland have been developing over the last 10 years.

--> calculating cross rates

--> comparing PPP and exchange rate

--> analyzing whether the currencies are overvalued or undervalued over the recent ten years