(1)在甲商店合算,因为在甲商店能买两幅球拍和25个球,而乙只能买到24个球,25=(90/0.9-25x2)/2,24=2x2+(90-25x2)/2
(2)设买x个球是两家一样划算:
(25+25)0.9+1.8x=50+2(x-4) 解得:x=15
(1)在甲商店合算,因为在甲商店能买两幅球拍和25个球,而乙只能买到24个球,25=(90/0.9-25x2)/2,24=2x2+(90-25x2)/2
(2)设买x个球是两家一样划算:
(25+25)0.9+1.8x=50+2(x-4) 解得:x=15