Bài 2. Thực hiện phép tính (bằng cách hợp lí nếu có thể).a)...

a) $\frac{8}{11}-1\frac{1}{4}+\frac{3}{14}-(\frac{-13}{21})+0.25=\frac{8}{11}-\frac{5}{4}+\frac{3}{14}+\frac{13}{21}+0.25=\frac{56}{77}-\frac{55}{44}+\frac{9}{77}+\frac{13}{21}+\frac{25}{100}=\frac{56}{77}-\frac{55}{44}+\frac{9}{77}+\frac{13}{21}+\frac{1}{4}=\frac{16}{77}+\frac{9}{77}+\frac{13}{21}=\frac{25}{77}+\frac{13}{21}=\frac{525}{1617}+\frac{819}{1617}=\frac{1344}{1617}=\frac{224}{269}$

b) $\frac{5}{8}\times 2\frac{2}{5}-\frac{5}{8}\times 1\frac{1}{3}=\frac{5}{8}\times \frac{12}{5}-\frac{5}{8}\times \frac{4}{3}=\frac{60}{40}-\frac{20}{24}=\frac{3}{2}-\frac{5}{6}=\frac{9}{6}-\frac{5}{6}=\frac{4}{6}=\frac{2}{3}$

c) $(\frac{4}{9}-\frac{3}{5})/1\frac{1}{5}+(\frac{5}{9}+\frac{1}{5})/1\frac{1}{5}=(\frac{20}{45}-\frac{27}{45})\div \frac{6}{5}+(\frac{25}{45}+\frac{9}{45})\div \frac{6}{5}=\frac{-7}{45}\div \frac{6}{5}+\frac{34}{45}\div \frac{6}{5}=\frac{-7}{45}\times \frac{5}{6}+\frac{34}{45}\times \frac{5}{6}=\frac{-35}{270}+\frac{170}{270}=\frac{135}{270}=\frac{1}{2}$

d) $\frac{6}{7}/(\frac{3}{26}-\frac{3}{13})+\frac{6}{7}/(\frac{1}{10}-\frac{8}{5})=\frac{6}{7}/(\frac{1}{26})+\frac{6}{7}/(\frac{-7}{10})=\frac{6}{7}\times \frac{26}{1}+\frac{6}{7}\times \frac{-10}{7}=\frac{156}{7}-\frac{60}{49}=\frac{156\cdot 7}{7\cdot 7}-\frac{60}{49}=\frac{1092-60}{49}=\frac{1032}{49}=21\frac{3}{49}$