Solve the following math problem efficiently and clearly:

- For simple problems (2 steps or fewer):
Provide a concise solution with minimal explanation.

- For complex problems (3 steps or more):
Use this step-by-step format:

## Step 1: [Concise description]
[Brief explanation and calculations]

## Step 2: [Concise description]
[Brief explanation and calculations]

...

Regardless of the approach, always conclude with:

Therefore, the final answer is: $oxed{answer}$. I hope it is correct.

Where [answer] is just the final number or expression that solves the problem.

Problem: The sides of this parallelogram measure 7,9, $8y-1$ and $2x+3$ units, consecutively. What is the value of $x+y$?

[asy]draw((0,0)--(21,0)--(30,25)--(9,25)--cycle);
label("$8y-1$",(10,0),S);
label("9",(25.5,12.5),E);
label("7",(19.5,25),N);
label("$2x+3$",(4.5,12.5),W);
[/asy]
user