#### Answer

$\frac{43}{8}$

#### Work Step by Step

To write $5\frac{3}{8}$ as a mixed number, we must multiply the whole number in front of the fraction and the denominator together.
$5\times8=40$
Next, take the sum of the number above and the numerator.
$40+3=43$
This will be the numerator of the mixed number. We will use the original denominator as the denominator of the mixed number. Therefore, $5\frac{3}{8}=\frac{43}{8}$.