Answer:
77
Step-by-step explanation:
Remark
The two angles (x and 103 add up to 180. In other words x + 103 = 180. You treat this like an ordinary equation.
Solution
Subtract 103 from both sides.
x + 103 - 103 = 180 - 103
x = 77
You can check this. The two angles not connected to x should add up to x
42 + 35 = 77
77 has been checked to be 77
