Hey there!
The equation is 180 = 35 + 12x + 1; x = 12
For this one, we can see that the two angles on top are supplementary angles, therefore they add up to 180°. So, that means that 180 = 35 + 12x + 1. Lets solve this now:
180 = 35 + 12x + 1
First, add like terms:
180 = 12x + 36
Next, subtract 36 from both sides:
144 = 12x
Lastly, divide both sides by 12:
12 = x
Therefore, x = 12
Hope you have a great day/night!