b= --6
So you multiply both sides by 6
6*5/6(12-5b)=35*6
Which would turn out to be
5(12-5b)= 210
Then divide both sides by 5
and you would get
5(12-5b)/5= 210/5
And you would get
12-5b=4
Then subtract 12 from both sides
12-5b-12= 42-12 which is
-5b=30
now divide both sides by 5 and you would get
-6