Answer
$b=-5$.
Work Step by Step
The given equation is
$\Rightarrow 6=1-b$
Subtract $1$ from each side.
$\Rightarrow 6-1=1-b-1$
Simplify.
$\Rightarrow 5=-b$
Multiply each side by $-1$.
$\Rightarrow -1(5)=-1(-b)$
Simplify.
$\Rightarrow -5=b$
Check:-
$\Rightarrow 6=1-(-5)$
$\Rightarrow 6=1+5$
$\Rightarrow 6=6$
True.
Hence, the solution is $b=-5$.
