What are the coordinates of a’ after reflecting across the line x = 3?

A is on the line x=3, so it goes nowhere when reflected across that line.

A' = (3, 2)

δabc ≅ δdcb by sas because

db ≅ ac . . given (side)

bc ≅ bc . . reflexive property (side)

∠dbc ≅ ∠ acb . . alternate interior angles where transversal bc crosses parallel lines bd and ac (included angle)