Răspuns:
[tex]\boxed{\frac{3655}{3}}[/tex]
Explicație pas cu pas:
[tex]\displaystyle{ \frac{1}{3} + \frac{2}{3} + \frac{3}{3} + ..... + \frac{85}{3} = \frac{1 + 2 + 3 + .... + 85}{3} }[/tex]
1 + 2 + 3 + ..... + 85 = (85 + 1) × 85 ÷ 2
= 86 ÷ 2 × 85
= 43 × 85
= 3655
[tex]\displaystyle{ \rightarrow \frac{1 + 2 + 3 + .... + 85}{3} = \frac{3655}{3} }[/tex]
