#### Answer

$y=-5$

#### Work Step by Step

We start with the given equation: $3y+5=-10$
We subtract $5$ from both sides of the equation: $3y+5-5=-5-10$
We combine like terms on both sides of the equation: $3y=-15$
We divide by $3$ on both sides of the equation: $y=\frac{-15}{3}=-5$