Answer:
The value of 'k' is -6.
Step-by-step explanation:
Given:
A line passing through the origin.
The points lying on the line are:
(5, 10) and 
A line that passes through the origin is given as:

Where 'm' is the slope of the line.
Now, (5, 10) lies on the line. So, the point will satisfy the equation.
Therefore, plugging in
in the above equation, we get:

So, the slope of the line is 2.
Now, the equation becomes 
Now, point (-3, k) will also satisfy the equation. So, plugging in
, we get

Therefore, the value of 'k' is -6.