To determine the value of $y$, we observe the geometric relationship in the triangle created by cutting the sandwich.

This is a right triangle where:

• One side is labeled $y$,
• The other side is labeled $2y$,
• The hypotenuse is the diagonal cut.

Using the Pythagorean theorem: $\text{Hypotenuse}^2 = \text{Opposite side}^2 + \text{Adjacent side}^2$

$\text{Diagonal}^2 = y^2 + (2y)^2$

Simplify the equation: $\text{Diagonal}^2 = y^2 + 4y^2$

$\text{Diagonal}^2 = 5y^2$

If more information is provided about the diagonal, substitute its value to solve for $y$. Otherwise, $y$ can be expressed in terms of the diagonal as: $y = \frac{\text{Diagonal}}{\sqrt{5}}$

Let me know if there are additional details to incorporate into this calculation! Do you have specific diagonal measurements, or do you need further clarification?

Relative questions:

1. What is the length of the diagonal cut of the sandwich?
2. Can you confirm if the sandwich forms a perfect right triangle?
3. Is there any additional information about the units of the sides?
4. Are there more sub-parts to this question to consider?
5. Could the diagonal's value be an irrational number?

Tip: Always cross-check the Pythagorean theorem's application for right triangles to ensure accurate solutions.