Substitute (x1,y1) = (2,9) and m = 4 into

y - y1 = m(x - x1)

 y - 9 = 4(x - 2)

That's it in point-slope form.  

If they had said to write your answer in slope-intercept 
form you would have had to take it further to the form y=mx+b:
 y-9=4x-8
   y=4x+1

Edwin