So the line is (-1,2,1) + t(1,1,3) ==> since the director vector (1,1,3) is not perpendicular to the given plane (for this the vector would have to be in the same direction as the plane's normal (2,-1,1), the line isn't perpendicular to the plane, but it crosses it: just plug the parametric values of x,y,z into the plane's eq. and find which t solves the equation.

Tonio