Find the measures of the angles marked $x$ and $y$. Remember that (1) the sum of the measures of the angles of a triangle is $180^{\circ}$, (2) supplementary angles have a sum of $180^{\circ}$.

Step 1 ：Let's assume we have a triangle ABC with angles A, B, and C. Angle A is marked as x and angle B is marked as y.

Step 2 ：We know that the sum of the angles in a triangle is 180 degrees. Therefore, we can write the equation as \(x + y + C = 180\).

Step 3 ：If we know the measure of angle C, we can find the measures of angles x and y by subtracting the measure of angle C from 180.

Step 4 ：\(x + y = 180 - C\)

Step 5 ：\(\boxed{x + y = 180 - C}\) is the sum of the angles marked as x and y, where C is the measure of the known angle.