Đáp án:

 $1)
a) \dfrac{-55}{78}\\
b) \dfrac{5}{30}\\
c) \dfrac{-9}{8}\\
d) \dfrac{75}{68}\\
e) \dfrac{-10}{3}\\
f) \dfrac{-3}{2}\\
g)
\dfrac{-39}{112}\\
h)
\dfrac{-35}{104}\\
2)
a)\dfrac{-13}{3}\\
b) \dfrac{-3}{2}\\
c) 
\dfrac{-2}{3}\\
d)
\dfrac{-11}{7}\\
3)
a) \dfrac{-2}{3}\\
b)
\dfrac{-2}{3}\\
c)
-49$

Giải thích các bước giải:

 $1)
a) \dfrac{-2}{3}+\dfrac{-1}{26}=\dfrac{-52}{78}+\dfrac{-3}{78}=\dfrac{-55}{78}\\
b) \dfrac{11}{30}-\dfrac{1}{5}=\dfrac{11}{30}-\dfrac{6}{30}=\dfrac{5}{30}\\
c) \dfrac{-9}{34}.\dfrac{17}{4}=\dfrac{-9}{17.2}.\dfrac{17}{4}=\dfrac{-9}{8}\\
d) 1\dfrac{1}{17}.1\dfrac{1}{24}=\dfrac{18}{17}.\dfrac{25}{24}=\dfrac{75}{68}\\
e) \dfrac{-5}{2}:\dfrac{3}{4}=\dfrac{-5}{2}.\dfrac{4}{3}=\dfrac{-10}{3}\\
f) 4\dfrac{1}{5}:(-2\dfrac{4}{5})=\dfrac{21}{5}:\dfrac{-14}{5}\\
=\dfrac{21}{5}.\dfrac{-5}{14}=\dfrac{-3}{2}\\
g)
\dfrac{-2}{7}+\dfrac{-1}{16}\\
=\dfrac{-32}{112}+\dfrac{-7}{112}=\dfrac{-39}{112}\\
h)
\dfrac{-3}{8}-\dfrac{-1}{26}\\
=\dfrac{-39}{104}+\dfrac{4}{104}\\
=\dfrac{-35}{104}\\
2)
a)\dfrac{2}{3}-4.\left ( \dfrac{1}{2}+\dfrac{3}{4} \right )\\
=\dfrac{2}{3}-4.\left ( \dfrac{2}{4}+\dfrac{3}{4} \right )\\
=\dfrac{2}{3}-4.\dfrac{5}{4}\\
=\dfrac{2}{3}-5\\
=\dfrac{2}{3}-\dfrac{15}{3}\\
=\dfrac{-13}{3}\\
b) \left ( \dfrac{-1}{3}+\dfrac{5}{6} \right ).11-7\\
=\left ( \dfrac{-2}{6}+\dfrac{5}{6} \right ).11-7\\
=\dfrac{3}{6}.11-7\\
=\dfrac{11}{2}-7\\
=\dfrac{11}{2}-\dfrac{14}{2}\\
=\dfrac{-3}{2}\\ c) 
\dfrac{-1}{24}-\left [ \dfrac{1}{4}-\left ( \dfrac{1}{2}-\dfrac{7}{8} \right ) \right ]\\
=\dfrac{-1}{24}-\left [ \dfrac{1}{4}-\left ( \dfrac{4}{8}-\dfrac{7}{8} \right ) \right ]\\
=\dfrac{-1}{24}-\left ( \dfrac{1}{4}-\dfrac{-3}{8} \right )\\
=\dfrac{-1}{24}-\left ( \dfrac{2}{8}-\dfrac{-3}{8} \right )\\
=\dfrac{-1}{24}-\dfrac{5}{8}\\
=\dfrac{-1}{24}-\dfrac{15}{24}\\
=\dfrac{-16}{24}=\dfrac{-2}{3}\\
d)
\left ( \dfrac{5}{7}-\dfrac{7}{5} \right )-\left [ \dfrac{1}{2}-\left ( -\dfrac{2}{7}-\dfrac{1}{10} \right ) \right ]\\
=\left ( \dfrac{25}{35}-\dfrac{49}{35} \right )-\left [ \dfrac{1}{2}-\left ( -\dfrac{20}{70}-\dfrac{7}{70} \right ) \right ]\\
=\dfrac{-24}{35}-\left ( \dfrac{1}{2}-\dfrac{-27}{70} \right )\\
=\dfrac{-24}{35}-\left ( \dfrac{35}{70}-\dfrac{-27}{70} \right )\\
=\dfrac{-24}{35}-\dfrac{62}{70}\\
=\dfrac{-24}{35}-\dfrac{31}{35}\\
=\dfrac{-55}{35}
=\dfrac{-11}{7}\\
3)
a) \left ( -\dfrac{2}{3} \right ).\dfrac{3}{11}+\left ( -\dfrac{16}{9} \right ).\dfrac{3}{11}\\
=\dfrac{3}{11}.\left ( \dfrac{-2}{3} +\dfrac{-16}{9}\right )\\
=\dfrac{3}{11}.\left ( \dfrac{-6}{9} +\dfrac{-16}{9}\right )\\
=\dfrac{3}{11}.\dfrac{-22}{9}\\
=\dfrac{-2}{3}\\
b)
\left ( \dfrac{1}{2}-\dfrac{13}{14} \right ):\dfrac{5}{7}-\left ( -\dfrac{2}{21}+\dfrac{1}{7} \right ):\dfrac{5}{7}\\
=\left ( \dfrac{7}{14}-\dfrac{13}{14} \right ).\dfrac{7}{5}-\left ( -\dfrac{2}{21}+\dfrac{3}{21} \right ).\dfrac{7}{5}\\
=\dfrac{-6}{14}.\dfrac{7}{5}-\dfrac{1}{21}.\dfrac{7}{5}\\
=\dfrac{7}{5}.\left ( \dfrac{-3}{7}-\dfrac{1}{21} \right )\\
=\dfrac{7}{5}.\left ( \dfrac{-9}{21}-\dfrac{1}{21} \right )\\
=\dfrac{7}{5}.\dfrac{-10}{21}\\
=\dfrac{-2}{3}\\
c)
\dfrac{4}{9}:\left ( -\dfrac{1}{7} \right )+6\dfrac{5}{9}:\left ( -\dfrac{1}{7} \right )\\
=\left ( \dfrac{4}{9} +\dfrac{59}{9}\right ):\dfrac{-1}{7}\\
=\dfrac{63}{9}.(-7)\\
=\dfrac{-441}{9}=-49$