We need to find the value of angle $y$, given that the other angle is $45$ degrees and the angles $y$ and $45$ degrees form a straight line.

1. Problem Description

We need to find the value of angle $y$, given that the other angle is $45$ degrees and the angles $y$ and $45$ degrees form a straight line.

2. Solution Steps

The angles $y$ and $45$ degrees are supplementary angles because they form a straight line. The sum of supplementary angles is $180$ degrees.

$$y + 45^{\circ} = 180^{\circ}$$

Now, subtract $45^{\circ}$ from both sides of the equation to solve for $y$:

$$y = 180^{\circ} - 45^{\circ}$$

$$y = 135^{\circ}$$

3. Final Answer

$y = 135^{\circ}$