The expression provided in the image is:

$-\left( y + 5 \right) - 3y$

Let's simplify this step-by-step.

1. Distribute the negative sign across the terms inside the parentheses:

$- (y + 5) = -y - 5$

Now the expression becomes:

$-y - 5 - 3y$

2. Combine the like terms, which are $-y$ and $-3y$:

$-y - 3y = -4y$

So, the simplified expression is:

$-4y - 5$

The fully simplified form is:

$-4y - 5$

Would you like further details or have any questions about this?

Here are five related questions for further practice:

1. Simplify $-(2x + 3) - 4x$.
2. Expand and simplify $-(x - 7) + 2x$.
3. What is the result of simplifying $- (3y + 4) + 5y$?
4. How do you distribute a negative sign over a binomial, such as $- (a + b)$?
5. Solve for $y$ if $-4y - 5 = 3$.

Tip: Always be careful with distributing negative signs across terms in parentheses, as it's a common source of mistakes.