Angle HJK is given and is 63 degrees, then angle HJK is a number added to 63 that makes 180 degrees. Angle HJK is 117. That means angle AHI is a number plus 117 = 180. Angle AHI is 63. A triangle makes 180 degrees total no matter what so if we have two angle measures we can add them and subtract from 180. 63 + 45 = 108. 180-108= 72 degrees :)