For questions 5 and 6 the angle of the arc will always be half of the total angle of the outer edge of a circle. So for 5 you divide 194 by 2 which gives you 97.
For 6 is the same so divide 144 by 2 which is 72
7 and 8 are different questions from 5 and 6 and use their own method for a solution.
7 requires understanding that opposite angles when lines are crossed equal each other. For 7 the two angles will be 85 and opposite it is 85 so add them together and subtract from 360 which is the total angle of a circle. Which is 190 and divide that by 2 which is 95. So angle D for 7 is 95 degrees. 8 is just an opposite angle so it’s 120 degrees