B I think, you shouldn’t trust me but ok
Answer: They are incorrect
Step-by-step explanation: They are incorrect because 12+15=27 and 20+9=29 so it won't work out because the numbers need to be equal. I hope this helps!
It would be x = 18
You can get this by adding/subtracting common values. If you get all the x values on one side and all constants on the other side, you end up with
2x = 36
and all you have to do is divide by 2 to get x = 18.