## Precalculus (6th Edition)

$B=\dfrac{2A}{h}-b$
$A=\dfrac{1}{2}h(B+b)$ $,$ for $B$ Take the $2$ to multiply the left side: $2A=h(B+b)$ Take $h$ to divide the left side: $\dfrac{2A}{h}=B+b$ Take $b$ to subtract the left side: $\dfrac{2A}{h}-b=B$ Rearrange: $B=\dfrac{2A}{h}-b$