Answer:
[tex] \displaystyle A .20[/tex]
Step-by-step explanation:
By tangent theorem we acquire:
[tex] \displaystyle x + 10 = 9 + 21[/tex]
simplify addition:
[tex] \displaystyle x + 10 = 30[/tex]
cancel 10 from both sides:
[tex] \displaystyle x = 20[/tex]
hence,
our answer is A
