To write 1/12 as a decimal you would do 1 divided by 12. 1 goes into 12 0 times, giving you a 0 in the ones place. You would the do 120 divided by 12, giving you 10. Therefore, 1/12 as a decimal is 0.10, simplified to 0.1
The answer is B. It's B because a straight line has a degree of 180, if you have 2, then of course it becomes 360. In B, you have 90, 90, and 150. If one of the angles is 30, you add that onto 150 to get 180 and add 90 and 90 together to get 180. Naturally, add those two answers together to get 360.
[(21 + 5) ÷ 2] + 7 × (8 - 3)
[26 ÷ 2] + 7 × (8 - 3)
13 + 7 × (8 - 3)
13 + 7 × 5
13 + 35
48