0.64X+0.89Y=2485.58
64X+89Y=248558
X=(248558-89Y)/64=3883-Y+(46-25Y)/64。令(46-25Y)/64=a則X=3883-Y+a
64a=46-25Y，Y=(46-64a)/25=1-2a+(21-14a)/25。令(21-14a)/25=b則Y=1-2a+b
25b=21-14a，a=(21-25b)/14=1-b+(7-11b)/14。令(7-11b)/14=c則a=1-b+c
14c=7-11b，b=(7-14c)/11=(7-3c)/11-c。令(7-3c)/11=d則b=d-c
11d=7-3c，c=(7-11d)/3=2-3d+(1-2d)/3。令(1-2d)/3=e則c=2-3d+e
3e=1-2d，d=(1-3e)/2=(1-e)/2-e。令(1-e)/2=f則d=f-e
2f=1-e，e=1-2f。
d=f-e=f-(1-2f)=f-1+2f=3f-1
c=2-3d+e=2-3(3f-1)+(1-2f)=2-9f+3+1-2f=6-11f
b=d-c=3f-1-(6-11f)=3f-1-6+11f=14f-7
a=1-b+c=1-(14f-7)+6-11f=1-14f+7+6-11f=14-25f
Y=1-2a+b=1-2(14-25f)+14f-7=1-28+50f+14f-7=64f-34
X=3883-Y+a=3883-(64f-34)+14-25f=3883-64f+34+14-25f=3931-89f
Y>=0 64f-34>=0 64f>=34 f>=34/64=17/32
X>=0 3931-89f>=0 89f<=3931 f<=3931/89
f.....X.....Y
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