Answer:
x = 60°
Step-by-step explanation:
AOB Center: O AB: diameter
arc ADB = 180°
arc DB = 180 - arc AD = 80°
x = 1/2 x ( arc DB + arc AC) = 1/2 x (80 + 40) = 60°
x=-4 x=-2
x² + 6x + 8 = 0
x² +2x+4x + 8 = 0
x(x+2)+4(x+2)=0
(x+4)(x+2)
The answer is 5!!