Note that vertical angles and corresponding angles are congruent.
From the figure,
1 and 4 are vertical angles, they are congruent
1 and 5 are corresponding angles, they are congruent
5 and 8 are vertical angles, they are congruent
The remaining angles will be supplementary to angle 1.
To summarize :
Congruent angles to angle 1 are
4, 5 and 8
