Answer
$\frac{11y}{24}$
Work Step by Step
By inspection, we see that the LCM of the denominators is $24$. Therefore, we create a common denominator using this LCM and obtain:
$\frac{5y}{6}-\frac{3y}{8}$
=$\frac{4(5y)-3(3y)}{24}$
=$\frac{20y-9y}{24}$
=$\frac{11y}{24}$