(a)
Equation of line $x + 2y + \mathcal{z} - 1 + \lambda\left( - x + y - 2\mathcal{z} - 2 \right) = 0$ (i)
$x + y - 2 + \mu\left( x + \mathcal{z} - 2 \right) = 0$ (ii)
(0, 0, 1) lies on it $\Rightarrow \lambda = 0,\ \mu = - 2$
For point of intersection, $\mathcal{z} = 0$ and solve (i) and (ii)