100x(1+25%)+80(2800-x)(1+10%)=3140
125x+80(1+10%)(2800-x)=3140
125x+8(2800-x)/11=3140
等式两边同时乘以11得
1375x+22400-8x=34540
1367x=12140
x≈8.88
100x(1+25%)+80(2800-x)(1+10%)=3140
125x+80(1+10%)(2800-x)=3140
125x+8(2800-x)/11=3140
等式两边同时乘以11得
1375x+22400-8x=34540
1367x=12140
x≈8.88