Tính  \(\dfrac{2}{7} + \left( {\dfrac{{ - 3}}{5}} \right) + \dfrac{3}{5},\) ta được kết quả là:

\(\frac{5}{{21}}\)

\(\frac{2}{7}\)

\(\frac{{23}}{{21}}\)

\(\frac{{-23}}{{21}}\)

0

\(\frac{4}{9}\)

\(\begin{array}{l}\frac{{ - 4}}{3}\\\end{array}\)

\(\frac{{ - 68}}{{75}}\)

$\dfrac{2}{{ - \,5}}$

$\dfrac{3}{4}$

$\dfrac{2}{3}$

$\dfrac{3}{2}$

\(\dfrac{2}{3} + \dfrac{5}{4}\)

\(\dfrac{1}{6} + \dfrac{3}{2}\)

\(\dfrac{5}{3} + \dfrac{3}{2}\)          

\(1 + \dfrac{{13}}{{12}}\)

\(\frac{{194}}{{45}}\)

\(3\frac{3}{5}\)

\(\frac{{ - 14}}{5}\)

\(\frac{{ - 85}}{{59}}\)

\(\frac{{16}}{{25}}\)

\(\frac{{ - 19}}{{25}}\)

\(\frac{{19}}{{25}}\)

\(\frac{{ - 16}}{{25}}\)

$ - \dfrac{{12}}{5}$   

$\dfrac{3}{4}$

$\dfrac{2}{{15}}$

$\dfrac{{12}}{5}$