Answer
$a>-7$.
Work Step by Step
The given inequality is
$\Rightarrow 6a-15<11a+20$
Subtract $6a$ from both sides.
$\Rightarrow 6a-15-6a<11a+20-6a$
Simplify.
$\Rightarrow -15<5a+20$
Subtract $20$ from both sides.
$\Rightarrow -15-20<5a+20-20$
Simplify.
$\Rightarrow -35<5a$
Divide both sides by $5$.
$\Rightarrow \frac{-35}{5}-7$.
