1) 2(х+3у)+9=х+6
3(х-2у)=х+30
2х+6у+9-х-6=0
3х-6у-х-30=0
х+6у+3=0
2х-6у-30=0
х+2х+6у+(-6у)+3+(-30)=0
3х+6у-6у+3-30=0
3х-27=0
3х=27
х=27/3
х=9
2(9+3у)+9=9+6
8+6у+9-9-6=0
12+6у=0
6у=-12
у=-12/6
у=-2
2(9+3*(-2))+9=2(9-6)+9=2*3+9=6+9=9+6
3((9-2*(-2))=3(9+4)=3*13=39=9+30
2) 5(3х+2)=7+12у
4(х+у)+х=31
15х+10-7-12у=0
4х+4у+х-31=0
15х+3-12у=0
5х+4у-31=0
15х+3-12у=0
3*5х+3*4у-3*31=0
15х+3-12у=0
15х+12у-93=0
15х+15х+3+(-93)-12у+12у=0
30х+3-93=0
30х-90=0
30х=90
х=90/30
х=3
5(3*3+2)=7+12у
5(9+2)-7-12у=0
5*11-7-12у=0
55-7-12у=0
48-12у=0
-12у=-48
у=-48/-12
у=4
5(3*3+2)=5(9+2)=5*11=55
7+12*4=7+48=55
4(3+4)+3=4*7+3=28+3=31