y-x=500 0.13x+0.13y=351
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y-x=5000.13x+0.13y=351y-x=5000.13x+0.13y=351y-x=5000.13x+0.13y=351y-x=500①0.13x+0.13y=351②由①得y=500+x
y-x=500 0.13x+0.13y=351
y-x=500 0.13x+0.13y=351
y-x=500 0.13x+0.13y=351
y-x=500 ①
0.13x+0.13y=351 ②
由①得y=500+x ③
将③代入②得0.13x+0.13(500+x)=351
0.26x+65=351
0.26x=286
x=1100
将x=1100代入③得y=500+1100=1600
楼上正解。
y-x=500 0.13x+0.13y=351
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