Okay, let's solve this system of equations.
First, let's rewrite the system to be clearer:
$$ \begin{cases} 2x + 1 = -1 \\ 5y + 3x = -1 \end{cases} $$
From the first equation, let's solve for x:
$$ 2x + 1 = -1 $$
$$ 2x = -1 - 1 $$
$$ 2x = -2 $$
$$ x = -1 $$
Now that we have the value for x, we can substitute it into the second equation to solve for y:
$$ 5y + 3x = -1 $$
$$ 5y + 3(-1) = -1 $$
$$ 5y - 3 = -1 $$
$$ 5y = -1 + 3 $$
$$ 5y = 2 $$
$$ y = \frac{2}{5} $$
So, the solution to the system of equations is:
$$ x = -1 $$
$$ y = \frac{2}{5} $$
Let's write the final answer.
Answer: x = -1, y = 2/5