(1)甲:(1200+600x)元中备 乙:{过程:[0.6×1200×(x+1)]元=} 答案:姿颂[720(x+1)]元迹培郑(2)1200+600x<720x+720 120x > 480 x >4
(1).1200+600x720+760x1200+600x<720+720x-120x<-480x>4