设甲成本为x,乙成本为y,
则x+y=300,
[x*(1+30%)*0.9+y*(1+20%)*0.9]-300=27.6
1.3x*0.9+1.2y*0.9=327.6
1.17x+1.08y=327.6
将x+y=300变形为y=300-x代入上式,
1.17x+1.08*(300-x)=327.6
1.17x +324-1.08x=327.6
0.09x=3.6
x=40元
所以甲商品成本是40元
设甲成本为x,乙成本为y,
则x+y=300,
[x*(1+30%)*0.9+y*(1+20%)*0.9]-300=27.6
1.3x*0.9+1.2y*0.9=327.6
1.17x+1.08y=327.6
将x+y=300变形为y=300-x代入上式,
1.17x+1.08*(300-x)=327.6
1.17x +324-1.08x=327.6
0.09x=3.6
x=40元
所以甲商品成本是40元