\[\boxed{\text{4.\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ x = - 5;\ \ x = - 10.\]
\[\textbf{б)}\ x = 2,5;\ \ \ x = - 1\frac{2}{3}.\]
\[\textbf{в)}\ x = - 2;\ \ x = 5,4.\]