The answer to your question is option b
Answer: 80 degrees because a line is 180°.
So if you subtract
180 - 100 = 80°
The answer is 12 but the way you get it is you subtract 400 from 1000 which gives you 600 then you divide 600 by 50 to get 12. So it looks like this 1000-400= 600, 600/50=12. Hope this helps. :)