x/0.6+4y=10.4 3/4x+0.5y=39/20
x+2.4y=6.24 0.75x+0.5y=1.95
0.75x+1.8y=4.68 0.75x+0.5y=1.95
（0.75x-0.75x）+（1.8y-0.5y）=4.68-1.95
1.3y=2.73 y=2.1
所以x=1.2