$\frac{2}{6}+\frac{1}{6}+\frac{1}{6}+\frac{2}{6}=\frac{6}{6}=1$ $\frac{1}{5}+\frac{3}{5}+\frac{0}{5}=\frac{1+3}{5}=\frac{4}{5}$ $\frac{6}{8}-\frac{2}{8}+\frac{3}{8}=\frac{7}{8}$ $\frac{2}{3}-\frac{1}{3}=\frac{1}{3}$