Find the algebraic equation of the plane that passes through the origin, is parallel to the line $\mathbf X= (-1, 0, 2) +t(2,-1,1)$, and contains the point $P=(1,2,3)$.

I suspect you can do this with a cross-product, but our professor isn't letting us use that as he hasn't taught it to us yet. Is there a way to get another point on the plane from the parallel line, so you can make a system of equations to solve for an orthogonal vector?