M represents the slope of a straight line where (x1,y1) is a point by which this straight line passes through. according to our givens in here this point is (3,4) (by substituting in the previous equation)
(multiplying both sides by (x-3)) 2(x-3)= y-4 2x - 2*3 = y - 4 2 x- 6 = y - 4 (by adding 4 to both sides) y - 4 +4 = 2x -6 +4 y = 2 x -2