Вопрос в картинках...

$log_{ \frac{10}{3} } (1-1.4x)\ \textless \ -1$
ОДЗ:
$1-1.4x\ \textgreater \ 0$
$-1.4x\ \textgreater \ -1$
$1.4x\ \textless \ 1$
$x\ \textless \ \frac{5}{7}$

$log_{ \frac{10}{3} } (1-1.4x)\ \textless \ log_{ \frac{10}{3} }0.3$
$1-1.4x\ \textless \ 0.3$
$-1.4x\ \textless \ 0.3-1$
$-1.4x\ \textless \ -0.7$
$x\ \textgreater \ 0.5$

-------------(0.5)----------------
///////////////////
-----------------------(5/7)--------
////////////////////////////

Ответ: $(0.5; \frac{5}{7} )$