Complex sentence: Tabubil is the base of operations for the Ok Tedi Copper Mine, the largest economic entity in the Western Province, accounting for over half of the entire province's economy and 25.7% of the country's entire export earnings.
Split into simpler sentences: Tabubil is the base of operations for the Ok Tedi Copper Mine, the largest economic entity in the Western Province. The mine accounts for over half of the entire province's economy and 25.7% of the country's entire export earnings.