把x=65,y=55 x=75, y=45代入y=kx+b得k=-1 b=120则可列方程:(x-60)(120-x)=500解知拦得x1=110 x2=70因为获利不得高于45%,所以x≤60(1+45%)配悄即x≤87所培猛渣以x=70