2分之1x-3分之2y=-15分之220y-15x=4………………①2分之1x-3分之5y=-3分之410y - 3x = 8………………③③×5得50y-15x = 40………………④③×2得20y - 6x = 16………………⑤④-①得30y = 36y = 1.2⑤ - ①得9x = 12x = 4/3
