Complex sentence: Its development represented a total of 2.6 million manhours worth of work, 9,600 of them in Germany, at a total cost of 1.9 billion euros, which makes it one of the most expensive Leopard 2s built.
Split into simpler sentences: Its development represented a total of 2.6 million manhours worth of work, 9,600 of them in Germany, at a total cost of 1.9 billion euros. This makes it one of the most expensive Leopard 2s built.