Answer:
The correct option is A.
Step-by-step explanation:
Line A and B are parallel lines.
[tex]\angle 1=3x[/tex] ....(1) (Alternate exterior angles)
[tex]\angle 1+9x=180[/tex] (Supplementary angles)
[tex]3x+9x=180[/tex]
[tex]12x=180[/tex]
[tex]x=15[/tex]
The value of x is 15.
Put this value in equation (1).
[tex]\angle 1=3\times 15=45[/tex]
Therefore measures of angle 1 is 45° and option A is correct.
