#### Answer

$\frac{x+3}{7}$

#### Work Step by Step

To simplify, divide both the numerator and denominator by their greatest common factor.
Use the distributive property to find the GCF.
$\frac{7x+21}{49}=\frac{7(x+3)}{49}=\frac{7(x+3)\div7}{49\div7}=\frac{x+3}{7}$