Two point charges with $1=2105$ C$,$ and $2=4105$ C$,$ are located in free space at points

with Cartesian coordinates $(1,3,-1)$ and $(-3,1,-2),$ respectively. Find $($a$)$ the electric field E at $(3,1,-2)$

and $($b$)$ the force on a $8105$ C charge located at that point. All distances are in meters.