#### Answer

$\displaystyle \frac{3x}{5}$

#### Work Step by Step

To add rational expressions with the same denominator,
add numerators and place the sum over the common denominator.
If possible, factor and simplify the result.
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$\displaystyle \frac{8x}{15}+\frac{x}{15} = \displaystyle \frac{8x+x}{15}$
$=\displaystyle \frac{9x}{15}$
$=\displaystyle \frac{3(3x)}{3(5)}\qquad$... reduce by 3
$=\displaystyle \frac{3x}{5}$