Answer:
Step-by-step explanation:
? + 86 + 90 + 84 + 36 = 360
? = 360 - 86 - 90 - 84 - 36
? = 64
therefore, the missing angle = 64°
x = -7 and x = 3
x² + 4x - 21 = 0 factors as follows: (x + 7)(x - 3) = 0.
Then x = -7 and x = 3.
B