Answer: [tex]54\°[/tex]
Step-by-step explanation:
Angles 1 and 3 are opposite angles, and in geometry there is a rule related to these type of angles:
"All opposite angles (angles opposed by the vertex) are equal"
Hence, if angle 3 measures [tex]54\°[/tex] angle 1 meaures [tex]54\°[/tex] as well.
