The triangle angle rule says that all of the angles in a triangle will add up to equal 180. So to find x we subtract the given angles ( 45 and 60 in this case) from 180.
x = 180-60-45
180-60-45=75
so x = 75
To find y we know that angle x and and y are angles formed on a straight line that are split up by a triangle segment. These angles are called supplementary angles which add up to equal 180.
So knowing that angle x = 75 we can find angle y by subtracting 75 from 180
180-75=105 so y = 105
Another way we could solve for y is the exterior triangle rule
This rule states that an exterior angle of a triangle is equal to the two opposite interior angles
