One of the outer corners of a triangle is 120 degrees; the angle not adjacent to it is 45 degrees

One of the outer corners of a triangle is 120 degrees; the angle not adjacent to it is 45 degrees find all the corners of the triangle

To solve this problem, you need to know 2 main rules:
1. The sum of all interior angles of a triangle is 180 °
2. The outer angle of a triangle is equal to the sum of two angles of a triangle that are not adjacent to it.
We know the outer corner. For x we take one of the angles not adjacent to it, the other angle is 45 °. 120 = x + 45; then x = 75 °
The two interior angles are now known. We can find the third: if the sum of the angles is 180 °, then 180 = x + 45 + 75, then x = 60
Answer: The angles are 45 °, 60 ° and 75 °.