解方程DD

(0.2+x)*0.88-x=84
解： 0.176+0.88x-x =84
0.176+(1-0.88)x=84
0.176+0.12x =84
0.176+0.12x-0.176=84-0.176
0.12x = 83.824
0.12x/0.12=83.824/0.12
x=10478/15

解:0.2*0.88+0.88x-x=84
-0.12x=83.824
x=-10478/15

解;（0.2+Ⅹ)×0.88=84+Ⅹ
(0.2+Ⅹ)×88=8400+100Ⅹ
17.6+88Ⅹ=8400+100Ⅹ
-12Ⅹ=8382.4
Ⅹ=-8382.4/12
Ⅹ=-2095.6/3
Ⅹ＝－10478/15

解;（0.2+X)×0.88=84+X
(0.2+X)×88=8400+100X
17.6+88X=8400+100X
-12X=8382.4
X=-8382.4/12
X=-2095.6/3
X=－10478/15