from the graph y=-7/4x
then
y=14*(-7/4)=-49/2

i am not seeking a solution how do i get the slope without using k ? and how do i find out about the y intercept

you can get the slope using this formula:

(y2 - y1) / (x2 - x1 )

here, it equals: (k - 7) / (14 - (-4)) = (k-7)/18

but u want to get the slope without using k, so use another pair of point: (0,0) and (-4,7)
which means the slope equals -7/4

and -7/4 = (k - 7)/18 ----> k = 98/ 4 = 24.5

also, since the line passes through point (0,0), the y intercept is (0,0).

now you can apply point (-4,7) to get k.

y = [(k-7)/18] x
7 = [(k-7)/18] (-4) ---> k = 98/ 4 = 24.5

Thank you salar_snake