7*х-(3+2*х)=х+9
7*х-3-2*х=х+9
5*x-3=x+9
5*x-3-x-9=0
4*x-12=0
4*x=12
x=12/4
x=3
13-(2*х-5)=х-3
13-2*х+5=х-3
18-2*х=х-3
18-2*х-х+3=0
21-3*x=0
-3*x=-21
3*x=21
x=21/3
x=7
3*х-(10-9*х)=22*х
3*x-10+9*х=22*х
12*x-10=22*x
12*x-10-22*x=0
-10*x-10=0
-10*x=10
x=10/(-10)
x=-1
26-(17-2*х)=5*х
26-17+2*х=5*х
9+2*x=5*x
9+2*x-5*x=0
9-3*x=0
-3*x=-9
3*x=9
x=9/3
x=3