由(1)得15(x-1)=y+515x-15=y+5∴y=15x-20 (3)由(2)得5y-5=3x+153x-5y=-20 (4)(3)代入(4)得3x-75x+100=-20-72x=-120x=5/3把 x=5/3代入(3)得y=25-20∴y=5∴方程组的解是x=5/3y=5