In which one of the following countries are 75 per cent of seats in both Houses of Parliament filled on the basis of first-past-the-post system and 25 per cent on the basis of Proportional Representation system of elections?

1. The question asks to identify a country employing a specific mixed electoral system: 75% First-Past-the-Post (FPTP) seats and 25% Proportional Representation (PR) seats for both Houses of Parliament. 2. Germany uses a Mixed Member Proportional (MMP) system, but the allocation is roughly 50% constituency seats (FPTP) and 50% list seats (PR), with PR vote share determining overall party proportions. 3. France uses a two-round majority system for most elections. 4. Russia has used various systems over time, including mixed systems, but not typically this 75/25 split. 5. Italy adopted the 'Mattarellum' law in 1993, which was in effect until 2005. This system allocated 75% of the seats in both its Chamber of Deputies and Senate via FPTP in single-member constituencies, and the remaining 25% via PR using party lists. This precisely matches the description in the question for the relevant period (around 1997).