Tính: a) -1/2 + 5/6 + 1/3; b) -3/8 + 7/4 - 1/12; c) 3/5 : (1/4 . 7/5)

* Hướng dẫn giải

a) $\frac{-1}{2}+\frac{5}{6}+\frac{1}{3}=\frac{\left(-1\right).3}{2.3}+\frac{5}{6}+\frac{1.2}{3.2}$$=\frac{2}{3}$

b) $\frac{-3}{8}+\frac{7}{4}-\frac{1}{12}=\frac{\left(-3\right).3}{8.3}+\frac{7.6}{4.6}-\frac{1.2}{12.2}$$=\frac{31}{24}$

c) $\frac{3}{5}:\left(\frac{1}{4}.\frac{7}{5}\right)=\frac{3}{5}:\frac{1.7}{4.5}=\frac{3}{5}:\frac{7}{20}=\frac{12}{7}$

d) $\frac{10}{11}+\frac{4}{11}:4-\frac{1}{8}=\frac{10}{11}+\frac{1}{11}-\frac{1}{8}$

$=1-\frac{1}{8}=\frac{8}{8}-\frac{1}{8}=\frac{7}{8}$