Answer
H
Work Step by Step
Use cross multiplication to solve for b.
$\frac{3}{b}=\frac{7}{8-b}\longrightarrow$ cross multiply
$3(8-b)=7b\longrightarrow$ multiply using distributive property
$24-3b=7b\longrightarrow$ add 3b to each side
$24-3b+3b=7b+3b\longrightarrow$ add
$24=10b\longrightarrow$ multiply each side by 10
$\frac{24}{10}=\frac{10b}{10}\longrightarrow$ reduce
$\frac{12}{5}=b$
