No, you can't use the law of syllogism because the statements are wrong. Supplementary angles measures up to only 180 NOT 190. An angle that is greater than 190 degrees is called a reflex angle. If you need more help I'm here.
It's 300 because you divide 60 by 12 which gives you 5, then multiply 60 and 5.
Answer: The answer would be x = -11/3, -3/5
