Space geometry

Find the value of a parameter $a\in \mathbb{R}$ so that the point $D=[-2;1;1]$ lies on the straight line $p$ defined by the parametric equations $$\begin{array}{rl}p:x& =1+m,\\ y& =-2+m,\\ z& =a+m;m\in \mathbb{R}.\end{array}$$

Find the value of a parameter $a\in \mathbb{R}$ so that the point $B=[1;4;5]$ lies on the straight line $p$ defined by the parametric equations $$\begin{array}{rl}p:x& =-1+m,\\ y& =2+am,\\ z& =3+m;m\in \mathbb{R}.\end{array}$$

From the given options choose the parametric equations which describe a straight line $p$ passing through the points $A=[-2;0;1]$ and $B=[2;0;-3]$.

A rectangle-based right pyramid $ABCDV$ with its bottom edge length of $6$ units and the perpendicular height of $6$ units is placed in a coordinate system (see the picture). Find the parametric equations of an intersection line $p$ of planes $\alpha$ and $\beta$, where $\alpha$ passes through the points $B$, $C$ and $V$, and $\beta$ passes through the points $A$, $D$ and $V$. What is the measure of an angle $\phi$ between the planes $\alpha$ and $\beta$. Round $\phi$ to the nearest minute.