13-100х=0
-100х=-13
х=13:100
х=0,13
7х-4=х-16
7х-х=-16+4
6х=-12
х=-2
13-5х=8-2х
-5х+2х=8-13
-3х=-5
х=5/3
4у+15=6у+17
4у-6у=17-15
-2у=2
у=-1
5х+(3х-7)=9
8х=9+7
8х=16
х=2
3у-(5-у)=11
3у-5+у=11
4у=11+5
4у=16
у=4
13-(5х+11)=6х
13-5х-11=6х
-11х=2
х=-2/11
(7х+1)-(6х+3)=5
7х+1-6х-3=5
х=7
(5х+2)-(4х+7)=8
5х+2-4х-7=8
х=8+5
х=13