x-4/1+9=10/9x 怎么算?还有：49x+51*(x-7)=81*100 (x-25)+(1-5%)(325-x

x-4/1+9=10/9x
0.1x=-8.75
x=-87.5
49x+51*(x-7)=81*100
49x+51x-357=8100
100x=8457
x=84.57
(x-25)+(1-5%)(325-x)=341
x+0.95(325-x)=366
x+308.75-0.95x=366
0.05x=57.25
x=1145
0.36x+11/10*0.36x+11/10*0.36x-16=x
(1+11/10+11/10)*0.36x-16=x
11/31*0.36x-x=16
11/11.16x-x=16
11/0.16x=16
x=1100