7.5x+4.5x=20
(x-22)+(x-24)+(x-27)+(x-20)=x
解方程 7.5x+4.5x=20 x=?
1.30x+20*7.5x=540
(x+2005)/ (x+2004)+(x+2007)/(x+2006)=(x+2008)/(x+2007)+(x+20
(X+X)+(X-X)+(X*X)+(X/X)=100
0.88(X+20%X)=X+84
x+24=4.5X
(20-2x)(20-2x)x>400 x=?
(X+X*20%)-[(1200-X)-(1200-X)*20%]=40%
X+X*20%-(1200-X)-(1200-X)*20%=40%
x-30%x=14x+25%x=20
x-3(20-x)=3x-7(9-x)