接着
设甲中酒精体积X,乙中酒精体积Y.由题,得方程组:(0.7X+0.6Y)/(X+Y)=0.66[0.7(X-5)+0.6(Y-5)]/(X+Y-10)=0.6625.解二元一次方程组可得X Y,X=30 Y=20
