(1)2.65x+0.45x=31
3.1x=31
3.1x÷3.1=31÷3.1
x=10;
(2)x÷
×5 8
=1 4 5
x=132 25
x÷32 25
=1÷32 25
32 25
x=
;25 32
(3)
:4 9
=x:151 6
x=1 6
×154 9
x÷1 6
=1 6
÷20 3
1 6
x=40.