20%+80%(320-x)=320×40%

（X+320)×80%=X-128 X+(X+40)+(2X-20)=320 解方程x(x-4)=320 20+0.8x=x-14 112-4x=2x(80-4x) 七年级一元一次方程题20%+(1-20%)(320-x)=320×40% 2(x-2)+2=x+1 2(x-2)-3(4x-1)=9(1-x) x/3 -5 = (5-x)/2 2(x+1) /3=5(x+1) /6 -1 (1/5)x +1 =(2x+1)/4 (5-2)/2 - (4+x)/3 =1 x/3 -1 = (1-x)/2 (x-2)/2 - (3x-2)/4 =-1 11x+64-2x=100-9x 15-(8-5x)=7x+(4-3x) [1].x-16.4=80 [2]28-2x=13 [3]3x+2x=25 [4]32-2x=30 [5] [x+5]*8=320 [6]x-2分之1x=2 20%+80%(320-x)=320×40% [1].x-16.4=80 [2]28-2x=13 [3]3x+2x=25 [4]32-2x=30 [5] [x+5]*8=320 [6]x-2分之1x=2[1].x-16.4=80 [2]28-2x=13 [3]3x+2x=25 [4]32-2x=30 [5] [x+5]*8=320 [6]x-2分之1x=2 5*4x+x*x=80 x*x*(1/4)=20x 20%X+(1-2o%)(320-x)=320*40% 化简为一般式y=30*[4x^2+(100-2x)(80-2x)]+20[2x(100-2x)-2x(80-2x)] 4x-3x(20-x)=4求x 4x-3x(20-x)=5x x-20%x=4 x-20%x=4 请把下列算式改为用数学符号,是分式就写成分式,不要用/,^这些320/(x-10)-(320-80+10)/x-80/(x-10)=1320x-250(x-10)-80x=x(x-10)x^2-10x-320x+250x-2500+80x=0x^2-2500=0x1=50,x2=-50(舍去) 4x-3x(20-x)=5x-7x(20-x)