Hello!
So, when you have these cases you need to know that the whole angle equals 180° (because they are supplementary angles, they add to each other) then the unknown value and the value that was given add to 180°, and the internal angles of a triangle also add up to 180°. Therefore:
116.7 + x = 180°
x = 63.3 (Is angle number 1)
63.3 + 79.4 + x = 180°
x = 37.3° (Is angle number 2)
