Equation of a line is y = mx +c
m is the gradient, which is given as -3 so now you have:
y = -3x + c
Replace y and x with the given point and solve for c:
4 = -3(-2) + c
Simplify:
4 = 6 + c
Subtract 6 from both sides:
c = -2
The equation becomes:
y = -3x-2
