I can answer most of them!
Evaluate and answer in standard form:
3^-1 = 1/3
Answer:
The angle of A is 80°
Step-by-step explanation:
Given that angle A lies on a straight line which is 180°. So in order to find A, you have to substract 100° from 180° :
∠A + 100° = 180°
∠A = 180° - 100°
∠A = 80°