Check the picture below.
for "b", well, recall that the sum of all interior angles in a triangle is 180°.
for "a", "c" and "d", well, all those are just <u>intercepted arcs</u>.
Angle A is 150
Angle B is 30
Supplementary= 180, so....
Angle A + Angle B = 180
150 + 30= 180
hope this helps
10. is f 11. is a I dont know for 12 though
1) 543/1000
2) 54.3
You're welcome ;)