My guess is before the current date but not sure hope that helped and sorry I could not do more and always good luck
The straight line joining the points A(3,-5) and B(6,k) has a gradient of 4.
Gradient is the slope
So the slope of the line joining the points A(3,-5) and B(6,k) is 4
Slope of line joining two points = 
A(3,-5) and B(6,k) are (x1,y1) and (x2,y2)
slope = 
slope = 
We know slope =4

Cross multiply and solve for k
k + 5 = 12
k = 7
The value of k = 7
Divide both side by 2 ad you get x=80
Divid both sides by 3
x<-3
{x | x<-3}
3rd choice