3) 2 28/35 + 6 1/8

\(2\frac{28}{35}+6\frac{1}{8}=2\frac{4}{5}+6\frac{1}{8}=8+\frac{32}{40}+\frac{5}{40}=8\frac{37}{40}\).

Ответ: \(8\frac{37}{40}\).