Trigonometry question, please help!

hey people, here's the question that i have absolute no idea to answer...

Quote:

A triangle $\displaystyle ABC$ is right-angled at $\displaystyle B$

$\displaystyle D$ is the point on $\displaystyle AC$ such that $\displaystyle BD$ is perpendicular to $\displaystyle AC$

Let Angle $\displaystyle BAC$ = $\displaystyle x$

You are given that $\displaystyle 6AD + BC = 5AC$

Find $\displaystyle x$

I had drawn the diagram on my book but i have no idea what to do to find $\displaystyle x$

Please help, would be much appreciated.