很久没做,印象全无,我做了几遍还是算不对（1）0.61x+0.30(350-x)=167(2)210/x-700/y=3.5,25(x+y)=210+700+340

0.61x+0.30(350-x)=1670.61x+105-0.30x=1670.31x=167-1050.31x=62x=62/0.31x=200210/x-700/y=3.525（x+y）=210+700+34025(x+y)=1250x+y=1250/25x+y=50x=50-y210/(50-y)-700/y=3.5210/50-210/y-700/y=3.54.2-(210/y+7...