Prealgebra (7th Edition)

$\frac{3x-28}{21}$
$\frac{x}{7}$ -$\frac{4}{3}$ =$\frac{x\times3}{7\times3}$-$\frac{4\times7}{3\times7}$ LCD of 7 and 3 is 21 =$\frac{3x}{21}$ -$\frac{28}{21}$ = $\frac{3x-28}{21}$