Tính a) 7/12 - (-1/5) - 5/6 + 2/3 + (-1/5) b) 1/2 + (16/21 + 27/13) - (14/13 - 5/21)

* Hướng dẫn giải

a) $\frac{7}{12}-\left(-\frac{1}{5}\right)-\frac{5}{6}+\frac{2}{3}+\left(-\frac{1}{5}\right)=\frac{7}{12}+\frac{1}{5}-\frac{5}{6}+\frac{2}{3}-\frac{1}{5}$$=\frac{7}{12}-\frac{10}{12}+\frac{8}{12}=\frac{5}{12}$

b) $\frac{1}{2}+\left(\frac{16}{21}+\frac{27}{13}\right)-\left(\frac{14}{13}-\frac{5}{21}\right)=\frac{1}{2}+\frac{16}{21}+\frac{27}{13}-\frac{14}{13}+\frac{5}{21}$$=\frac{1}{2}+1+1=\frac{5}{2}$