Answer
$m\angle ABC=85-x$
Work Step by Step
The Angle Addition Postulate says:
$m\angle ABC + m\angle CBD = m\angle ABD$
Substitute the given values.
$m\angle ABC + x=85$
Subtract x from each side to solve for $\angle ABC$.
$m\angle ABC+x-x=85-x$
$m\angle ABC=85-x$
