Answer
$a-8$
Work Step by Step
Since the grouping symbol is preceded by a negative sign, then the sign of each term inside the grouping symbol alters once the grouping symbol is removed. Hence, the given expression, $
2a+5a-(6a+8)
$, is equivalent to
\begin{array}{l}\require{cancel}
2a+5a-6a-8
.\end{array}
By combining like terms, then this simplifies to
\begin{array}{l}\require{cancel}
a-8
.\end{array}
