Tính giá trị biểu thức sau theo cách hợp lí

\(\left( {\dfrac{{20}}{7}.\dfrac{{ - 4}}{{ - 5}}} \right) + \left( {\dfrac{{20}}{7}.\dfrac{3}{{ - 5}}} \right)\)

$1$ 

\(3\)  

\(\dfrac{1}{{ - 3}}\)    

\(\dfrac{1}{3}\)

\(\dfrac{{ - 2}}{{27}}\)                     

\(\dfrac{{ - 4}}{9}\)  

\(\dfrac{{ - 1}}{{18}}\)

\(\dfrac{{ - 3}}{2}\)

$\dfrac{1}{4}$ 

\(\dfrac{1}{2}\)          

\( - \dfrac{1}{2}\)                        

\(1\)

\({\left( {\dfrac{{ - 7}}{6}} \right)^2} = \dfrac{{ - 49}}{{36}}\) 

\({\left( {\dfrac{2}{3}} \right)^3} = \dfrac{8}{9}\)  

\({\left( {\dfrac{2}{{ - 3}}} \right)^3} = \dfrac{8}{{ - 27}}\)          

\({\left( {\dfrac{{ - 2}}{3}} \right)^4} = \dfrac{{ - 16}}{{81}}\)

$ - \dfrac{1}{{10}}$ 

\( - \dfrac{4}{9}\)  

\( - \dfrac{4}{3}\)                               

\( - 4\)

$\dfrac{7}{{18}}$ 

\(\dfrac{9}{{14}}\)     

\(\dfrac{{36}}{7}\)                      

\(\dfrac{{18}}{7}\)

$8$ 

\(\dfrac{9}{5}\)  

\(\dfrac{3}{5}\)          

\(2\)