(1000-20x)(25+x)=27000
25000+1000x-500x-20x2=27000
-20x2+500x-2000=0
-x2+25x-100=0
x2-25x+100=0
(x-5)x(x-20)=0
共两个解
x1=5
x2=20
(1000-20x)(25+x)=27000
25000+1000x-500x-20x2=27000
-20x2+500x-2000=0
-x2+25x-100=0
x2-25x+100=0
(x-5)x(x-20)=0
共两个解
x1=5
x2=20