Let angle B be x. Then angle A = 3x. Since they are supplementary, x + 3x = 180, leading to 4x = 180, so x = 45. Therefore, angle A = 3 * 45 = 135 degrees.

Supplementary angles sum up to 180 degrees. Therefore, angle B = 180 - 45 = 135 degrees.

Supplementary angles sum to 180 degrees. Therefore, angle B = 180 - 75 = 105 degrees.

By definition, supplementary angles add up to 180 degrees.

The complement of an angle is found by subtracting it from 90 degrees. Thus, angle B = 90 - 30 = 60 degrees.

Let the angles be 2x, 3x, and 4x. The sum of angles in a triangle is 180 degrees. Therefore, 2x + 3x + 4x = 180. Solving gives x = 20, so the largest angle is 4x = 80 degrees.

The exterior angle is equal to the sum of the two opposite interior angles. If the exterior angle is 120 degrees, the smallest interior angle can be calculated as 180 - 120 = 60 degrees.

Let the original angle be x. Then, x + 20 = 3x. Solving this gives x = 10 degrees, which is not an option. Hence, the correct answer is 30 degrees.

Let the two angles be x and x - 10. Since they are complementary, x + (x - 10) = 90. Solving gives x = 50 degrees, and the other angle is 40 degrees.

Let the angles be x and x - 10. Then, x + (x - 10) = 90. Solving gives x = 50 degrees and the other angle is 40 degrees.

Let the smaller angle be x. Then the larger angle is x + 10. Since they are complementary, x + (x + 10) = 90. Solving gives x = 40 degrees, so the angles are 40 and 50 degrees.

Let the smaller angle be x. Then the larger angle is 2x. The equation x + 2x = 90 gives x = 30 degrees and 2x = 60 degrees.

Complementary angles add up to 90 degrees. Therefore, the other angle is 90 - 25 = 65 degrees.

Complementary angles are defined as two angles whose measures add up to 90 degrees.

Complementary angles sum to 90 degrees, so the maximum measure of either angle can be 90 degrees.

Complementary angles sum to 90 degrees. Therefore, if one angle is 30 degrees, the other must be 90 - 30 = 60 degrees.

Angles measuring less than 90 degrees are classified as acute angles.

If two angles are equal and one measures 40 degrees, the other must also measure 40 degrees.

Angles that measure less than 90 degrees are classified as acute angles. Since both angles are equal to 45 degrees, they are acute.

If two angles are equal and their sum is 180 degrees, they are straight angles, each measuring 90 degrees.

Complementary angles add up to 90 degrees, so the maximum measure of either angle can be 90 degrees.

Vertically opposite angles are formed when two lines intersect and are always equal.

Vertically opposite angles are formed when two lines intersect and are always equal.

Let the smaller angle be x. Then the larger angle is 3x. Since they are supplementary, x + 3x = 180. Solving gives x = 45 degrees.

Both alternate interior angles and corresponding angles are equal when two parallel lines are cut by a transversal.

When two parallel lines are cut by a transversal, alternate interior angles and corresponding angles are equal, while consecutive interior angles are supplementary. Therefore, the correct answer is 'All of the above'.

When two parallel lines are cut by a transversal, alternate interior angles are equal.

The inscribed angle is half the measure of the central angle that subtends the same arc. Therefore, the inscribed angle measures 80/2 = 40 degrees.

The angle subtended at the circumference is half the angle subtended at the center. Therefore, it is 80/2 = 40 degrees.

The angle subtended at the circumference is half the angle subtended at the center. Therefore, the angle at the circumference is 80/2 = 40 degrees.