Answer
$\left\{ a|a\ge 1 \right\}
\text{ or }
\left[ 1,\infty \right)
$
Work Step by Step
Using the properties of inequality, the given inequality, $
6-5a\le a
,$ is equivalent to
\begin{array}{l}\require{cancel}
-5a-a\le -6
\\\\
-6a\le -6
\\\\
a\ge \dfrac{-6}{-6}
\\\\
a\ge 1
.\end{array}
Hence, the solution is $
\left\{ a|a\ge 1 \right\}
\text{ or }
\left[ 1,\infty \right)
.$
