3+4(5х-3)=4х+7
 3(5х-7)-7(4х+5)=х
 2(6х-5)-7(3х-5)=4х-1
-12х+4(х-3)=-8х-12

3+20х-12=4х+720х-4х=7-3+1216х=16х=115х-21-28х-35=х15х-28х-х=35+21-14х=56х=-412х-10-21х+35-4х=-1-13х=-1+10-35-13х=-26х=2-12х+4х-12+8х=-12-12=-12