This are the problems

Dear student

\frac{3}{7} + (- \frac{6}{11}) + (- \frac{8}{21}) + \frac{5}{22} = \frac{3}{7} - \frac{6}{11} - \frac{8}{21} + \frac{5}{22} = \frac{3 \times 66 - 6 \times 42 - 8 \times 22 + 5 \times 21}{462} = \frac{198 - 252 - 176 + 105}{462} = \frac{- 125}{462} Similarly try other parts

Regards