The sum of all angles in a pentagon is 540 degrees. Now that we know that, we can begin our equation:
100+102+108+121+x=540
Now, let's combine like terms: 431+x=540
Now, let's subtract 431 on both sides to figure out what x equals: x=109
Answer: x=109
If you have any further questions, please let me know in the comments of this answer! Thanks :)
