Firstly, you need to find the gradient, in the form
y=mx+c
The formula for gradient is
(y1-y2)/(x1-x2)
so
(5-1)/(-2--4) = 4/2 = 2
So you know that the line is y=2x+c
Now substitute one of the points into the equation
1=2(-4)+c
1=-8+c
so 9 = c
So the equation of the line is
y=2x+9