Find the value of ? in the equation: (815 ÷ ?) ÷ 100 × 28 × 3 − (815 × 14 × 6) ÷ 100 = 1680.

Explanation

Let the unknown number be x. The equation can be rewritten as (815 ÷ x) ÷ 100 × 28 × 3 − (815 × 14 × 6) ÷ 100 = 1680. Simplifying, we find that x equals 2000.