Write an equation given m=2 and (3 , 4)

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

Best answer that i found on yahoo ok   set :   x= length of 2nd piece in cm  x- 3= length of 1st piece in cm  x-4= length of 3rd piece in cm  then since you know they all came from the 20 cm ribbon you add them together and set them equal to 20x+ x-3 +x-4 = 20  3x - 7= 20  3x= 27  x= 9  the shortest piece is the third piece which is x- 4  x-4  9-4 = 5  the length of the smallest piece is 5 cm.  the other lengths are  9 cm  6 cm