A) To find the rate of brant A we will divide the coordinate y by the coordinate x in any point of the line so for example I use the coordinate: (4,9)

B) for the brand B I use the coordinate (2,3) so:

C) so in this case brand A is alwais more expensive than brand B
D)
if you bought 4 meters in brand A you will spend more or less 9 dollasr and in the brand 2 mor or less 6 dollars, so in total you save 3 dollars