(1)
x=40,5 8
x×5 8
=40×8 5
,8 5
x=64;
(2)x-x÷1
=1 3
,4 5
x-x×
=3 4
,4 5
x=1 4
,4 5
x×4=1 4
×4,4 5
x=3
;1 5
(3)24-120%x=18,
24+1.2x-1.2x=18+1.2x,
18+1.2x=24,
18-18+1.2x=24-18,
1.2x÷1.2=6÷1.2,
x=5.