Lg(5x-7) меньше или равно 3lg2

Lg(5x-7)≤3*lg2
lg(5x-7)≤lg2³
lg(5x-7)≤lg8
основание логарифма а=8, 8>1. знак неравенства не меняем:
$\left \{ {{5x-7\ \textgreater \ 0} \atop {5x-7 \leq 8}} \right. \left \{ {{5x\ \textgreater \ 7} \atop {5x \leq 15}} \right. \left \{ {{x\ \textgreater \ 1,7} \atop {x \leq 3}} \right.$

x∈(1,4; 3]