Solution - Simplification or other simple results

Reformatting the input :

Changes made to your input should not affect the solution:

(1): "1.05" was replaced by "(105/100)".

Step  1  :

            21
 Simplify   ——
            20

Equation at the end of step  1  :

        21
  800 • ——
        20

Step  2  :

Final result :

  840