100x:150x=3:4
是100x:150y=3:4 ,还是100y:150x=3:4y100x:150y=3:42x:3y=3:48x = 9yx+y=2009(x+y) = 9*2009x + 9y = 18009x + 8x = 180017x = 1800 x = 1800/17 y = 8/9 * x=8/9 * 1800/17= 1600/179x + 9y = 1800 9x + 8x = 1800不懂哦。。。。∵8x = 9y前面推导了∴9x + 9y = 9x + 8x