It looks like your instructor wants you to write in point-slope form.
the equation for point slope form is quite simple
y-y1=m(x-x1)
your variables:
y and x: just state these as they are
m: slope
y1 and x1: the numbers in the point given
keep in mind a double negative equals a positive, so when you come across a negative coordinate you would put + instead of - in your equation.
your final answer would be
y+2=-2(x-4)
I hope this helped :)
please don't hesitate to ask if you have any more questions
