Slopes of Perpendicular Lines

Suppose you are building a bookshelf and you want $2$ pieces of wood to intersect at a $90^{\circ}$ angle. The first piece of wood can be expressed as $y=x+6$. The second piece of wood has to intersect the point $(5,-2)$. What is the equation of the second piece of wood? Write your answer in the form $y=mx+b$.