(80-2x)(60-2x)=2400(40-x)(30-x)=600x^2-70x+600=0(x-10)(x-60)=0x=10 或 x=60
(80-2x)(60-2x)=2400(40 - x)*(30 - x) = 6001200 - 70x + x^2 = 600x^2 - 70 x + 600 = 0x = 60,10
设60-2x=t则80-2x=20+t接下来就会了8
