Question 455327
If these vectors are parallel, the slope of the line through (0,0) and (3,6) must be equal to the slope of the line through (0,0) and (-2,k).
The slope of the line through (0,0) and (3,6) is (6-0)/(3-0), or 2.
So the slope through (0,0) and (-2,k) must be 2.
(k-0)/(-2-0)=2
k/-2=2
k=-4