OG详解-OG1 数学1 Q18

Choice B is correct. The graph shown is a line passing through the points (0,40) and (60,0). Since the relationship between x and y is linear, if two points on the graph make a linear equation true, then the equation represents the relationship. Substituting 0 for x and 40 for y in the equation in choice 8x +12y = 480,yields 8(0)+12(40)= 480,or 480 = 480 ,which is true.Substituting 60 for x  and 0 for y  in the equation  8x +12y = 480 yields 8 (60)+12(0)= 480, or 480 = 480 , which is true. Therefore, the equation 8x +12y = 480 represents the relationship between x  and  y.
Choice A is incorrect. The point  (0,40) is not on the graph of this equation, since 40 = 8 (0)+12, or 40 = 12, is not true. Choice C is incorrect. The point  (0,40) is not on the graph of this equation, since  40 = 12 (0)+8, or  40 = 8, is not true. Choice D is incorrect. The point  (0,40) is not on the graph of this equation, since 12 (0)+8(40)= 480, or 320 = 480, is not true.