Answer
$\displaystyle \frac{y-7}{3y-7}$
Work Step by Step
To subtract rational expressions with the same denominator,
subtract numerators and place the difference over the common denominator.
If possible, factor and simplify the result.
---
Don't forget to place the second numerator in parentheses when subtracting.
$\displaystyle \frac{2y+1}{3y-7}-\frac{y+8}{3y-7}= \displaystyle \frac{2y+1-(y+8)}{3y-7}$
$= \displaystyle \frac{2y+1-y-8}{3y-7}$
$= \displaystyle \frac{y-7}{3y-7}$
