Answer
$(-∞,-1.5)$
Work Step by Step
$0.7x-x \gt 0.45$
$(0.7-1)x \gt 0.45$
$-0.3x \gt 0.45$
Divide both sides by $-0.3$ and reverse the inequality symbol.
$\frac{-0.3}{-0.3}x \lt \frac{0.45}{-0.3}$
$x \lt -1.5$
In interval notation, the solution set is $(-∞,-1.5)$