2.5780/85 *100 = 6800kg = 6.8 tons A: 6.8 tons of wheat are needed.

3.30/ 100=30%, 200*30%=60 A: 200 tons of lead ore contains 60 tons of lead.

4.208 * 3 * 3/4 = 1 17 Answer: If a square brick with a side length of 4 mm is used, 1 17 is required.