(1)x÷0.81=6.3,
x÷0.81×0.81=6.3×0.81,
x=5.103;
(2)3x-4×6.5=7.6,
3x-26+26=7.6+26,
3x÷3=33.6÷3,
x=11.2;
(3)12.5x+x=108,
13.5x=108,
13.5x÷13.5=108÷13.5,
x=8.
(1)x÷0.81=6.3,
x÷0.81×0.81=6.3×0.81,
x=5.103;
(2)3x-4×6.5=7.6,
3x-26+26=7.6+26,
3x÷3=33.6÷3,
x=11.2;
(3)12.5x+x=108,
13.5x=108,
13.5x÷13.5=108÷13.5,
x=8.