-4(1-6b)-5(2b-6)=8b-7b
We move all terms to the left:
-4(1-6b)-5(2b-6)-(8b-7b)=0
We add all the numbers together, and all the variables
-4(-6b+1)-5(2b-6)-(+b)=0
We multiply parentheses
24b-10b-(+b)-4+30=0
We get rid of parentheses
24b-10b-b-4+30=0
We add all the numbers together, and all the variables
13b+26=0
We move all terms containing b to the left, all other terms to the right
13b=-26
b=-26/13
b=-2