A because when you plug the points in every point works
Answer:
x=6
Step-by-step explanation:
5x+9-3x=21
5x-3x=21-9
2x=12
x=6
It’s D. I’ll show you in the picture below
Answer:
C
Step-by-step explanation:
Given
3
= 24 ( divide both sides by 3 )
= 8
Raise both sides to the power of 
x + 9 =
=
=
= 16 ( subtract 9 from both sides )
x = 7 → C