a)

$\begin{array}{l}x+\left(-\frac{1}{5}\right)=\frac{-4}{15}\\ x=\frac{-4}{15}+\frac{1}{5}\\ x=\frac{-4}{15}+\frac{3}{15}\\ x=\frac{-1}{15}\end{array}$                 

Vậy $x=\frac{-1}{15}$.

b)

$\begin{array}{l}3,7-x=\frac{7}{10}\\ x=3,7-\frac{7}{10}\\ x=\frac{37}{10}-\frac{7}{10}\\ x=3\end{array}$

Vậy $x=3$.

c)

$\begin{array}{l}x.\frac{3}{2}=2,4\\ x.\frac{3}{2}=\frac{12}{5}\\ x=\frac{12}{5}:\frac{3}{2}\\ x=\frac{12}{5}.\frac{2}{3}\\ x=\frac{8}{5}\end{array}$$\begin{array}{l}x.\frac{3}{2}=2,4\\ x.\frac{3}{2}=\frac{12}{5}\\ x=\frac{12}{5}:\frac{3}{2}\\ x=\frac{12}{5}.\frac{2}{3}\\ x=\frac{8}{5}\end{array}$           

Vậy $x=\frac{8}{5}$       

d)

$\begin{array}{l}3,2:x=-\frac{6}{11}\\ \frac{16}{5}:x=-\frac{6}{11}\\ x=\frac{16}{5}:\left(-\frac{6}{11}\right)\\ x=\frac{16}{5}.\frac{-11}{6}\\ x=\frac{-88}{15}\end{array}$

Vậy $x=\frac{-88}{15}$.