Answer: A) 21
Step-by-step explanation:
From the given figure, we can see that angles [tex]64^{\circ}[/tex] and [tex](3x+1)^{\circ}[/tex] are vertically opposite angles.
Since, vertically opposite angles are equal, therefore we have
[tex]64^{\circ}=(3x+1)^{\circ}\\\\\Rightarrow64=3x+1\\\\\text{Subtract 1 on both sides, we get}\\\\\Rightarrow3x=63\\\\\text{Divide 3 on both sides, we get}\\\\\Rightarrow x=21[/tex]
Hence, the value of x = 21.
