Understand futures.
1.(2020-2000)* 10*20+(2030-2000)* 10*80=28000 2.(2050-2000)* 10*30+(2035-2000)* 10*50+(28 10-2800)* 20 = 22700 3. (2030-2000) *10 * 50+(2820-2800) *10 * 20 =19000 The above figures are calculated only according to your topic requirements. But from beginning to end, you earned (2020-2000) *10 * 20+(2050-2000) *10 * 30+(2030-2000) *10 * 50+(.