#### Answer

$b=\dfrac{2A}{h}$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
To solve the given equation, $
A=\dfrac{1}{2}bh
$ for $
b
,$ use the properties of equality to isolate the variable.
$\bf{\text{Solution Details:}}$
Using the properties of equality to isolate the variable, the equation above is equivalent to
\begin{array}{l}\require{cancel}
A=\dfrac{1}{2}bh
\\\\
2\cdot A=2\cdot\dfrac{1}{2}bh
\\\\
2A=bh
\\\\
\dfrac{2A}{h}=\dfrac{bh}{h}
\\\\
\dfrac{2A}{h}=b
\\\\
b=\dfrac{2A}{h}
.\end{array}