解:5/9x-3+31=(1+20%)x
5/9x +28=1.2x
(1.2-5/9)x=-28
(54/45-25/45)x=-28
29/45x=-28
x=(-28*45)/29
5/9x-3+31=(1+20%)x
5/9x+28=120%x
5/9x-6/5x=-28
(10x-18x)/5=-28
-8x=-140
x=17.5
5/9x-3+31=1.2x
5/9x-5/6x=-28
10/18x-15/18x=-28
-5/18=-28
x=100.8