Let vec$(F)=$xvec$(i)+(x+y)vec(j)+(x-y+z)vec(k).$ Let the line $l$ be $x=-(2+5t),y=3+5t,z=-(1+4t).$

$($a$)$ Find a point $P=(x_0,y_0,z_0)$ where vec$(F)$ is parallel to $l.$

$P=$

Find a point $Q=(x_1,y_1,z_1)$ at which vec$(F)$ and $l$ are perpendicular.

$Q=$

Give an equation for the set of all points at which vec$(F)$ and $l$ are perpendicular.

equation: