Question

How do you solve for $b$ in $P=a+b+c$?

Answer 1

Solve the equation $\mathit{P}\mathbf{=}\mathit{a}\mathbf{+}\mathit{b}\mathbf{+}\mathit{c}$ for $\mathit{b}$.

The variable $b$ can be isolated in the equation $P=a+b+c$.

Subtracting $a+c$ from both sides of the equation:

$\begin{array}{rcl}P& =& a+b+c\\ & \Rightarrow & P-\left(a+c\right)=a+b+c-\left(a+c\right)\\ & \Rightarrow & P-a-c=a+b+c-a-c\\ & \Rightarrow & P-a-c=b\end{array}$

Hence, the value of $\mathit{b}\mathbf{=}\mathit{P}\mathbf{-}\mathit{a}\mathbf{-}\mathit{c}$.