5x-12x-42=13-x-1

5x-12x+x=-1+13+42

-6x=54

x=-9

5х-6(2х+7)=13-(х+1) 

5x-18x+42=13-(x+1)

5x-18x+(x+1)=13-42

-12x+(x+1)=-29

-12x+(x+1)=-29

(2x+1)=-17

2x=-17-1

x=-9