Answer:
x = 23
Explanation:
Since AC and BD are straight lines four angles formed at the intersection. The opposite angles are equal to each other
So,
x + 115 = 6x
Switch sides
6x = x + 115
Subtract x from both sides
== . 6x - x = x -x + 115
==> 5x = 115
Divide by 5 both sides
==> 5x/5 = 115/5
==> x = 23
Check values for both angles and see if they equal each other
x + 115 = 23 + 115 = 138
6x = 6 x 23 = 138
So everything checks out