2x-9=x
2x-x=9
x=9
x×4,2=0,4
4,2x=0,4:4,2
x=2/21
3 1/2:x=5/6
x=3 1/2:5/6
x=4 1/5
2 1/6+2,5x=4 1/3
2,5x=4 2/6-2 1/6
2,5x=2 1/6:2,5
x=13/15
3 3/4-2 1/4x=0,75
-2,25x=0,75-3,75
-2,25x=-3:(-2,25
x=300/225=1 75/225=1 15/45=1 1/3
7x+12-x-4=20
6x=20-12+4
6x=12:6
x=2