Keystone Steel Company has two departments, Casting and Rolling. In the Rolling Department, ingots from the Casting Department are rolled into steel sheet. The Rolling Department received 8, 500 tons from the Casting Department. During the period, the Rolling Department completed 7, 900 tons, including 400 tons of work in process at the beginning of the period. The ending work in process inventory was 1,000 tons. How many tons were started and completed during the period? tons