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最佳答案:(1)z=3x/7,y=3x/52x-y-z=342x-3x/5-3x/7=342x-36x/35=3434x/35=34∴x=35 ,y=21,z=15(2)
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最佳答案:1.3(x-1)=y+5即3x-3=y+53x-y=8 (1)5(y-1)=3(x+5)即5y-5=3x+153x-5y=-20 (2)(1)-(2)3x-y-