1. The problem is to substitute the value $b=4$ into an expression or equation involving $b$. 2. Since you provided only the value for $b$ without an expression, we'll understand this as assigning $4$ to the variable $b$. 3. Any expression containing $b$ now will use $b=4$. For example, if the expression is $2b + 3$, substituting $b=4$ yields: $$2\times 4 + 3 = 8 + 3 = 11$$ If you have a specific expression or equation to evaluate with $b=4$, please provide it!