0.5x+0.1y=2.8,------(1)
50%x+90%y/26=1/5------(2)
(1)*10,5x+y=28,y=28-5x------(3)
(2),130x+9y=52------(4)
(3)代入(4)得 130x+9(28-5x)=52,x=-40/17
y=28-5(-40/17)=39又13/17
0.5x+0.1y=2.8,------(1)
50%x+90%y/26=1/5------(2)
(1)*10,5x+y=28,y=28-5x------(3)
(2),130x+9y=52------(4)
(3)代入(4)得 130x+9(28-5x)=52,x=-40/17
y=28-5(-40/17)=39又13/17