Answer
$y+z=3$
Work Step by Step
Since, we have $-1+t=1-4s$ and $2+t=1+2s$
After solving, we get $s=\dfrac{1}{2}$ and $t=2-4s=2-4(1/2)=0$
The normal to the plane is $n=\lt 0,6,6 \gt$
We know that the standard equation of a plane passing through the point $(x_0,y_0,z_0)$ is written as: $a(x-x_0)+b(y-y_0)+c(z-z_0)=0$
Then for point $(-1,2,1)$, we have
$0(x+1)+6(y -2)+6(z-1)=0$
or, $6y+6z=18$
or, $y+z=3$
