Question

find alternate angle to <13, <15 and corresponding to angle 15​

Answer 1

Given the line n is transversal to line l and  m.

Then we know  

corresponding angles are equal

alternate interior angles are equal

Thus,

Alternate angle corresponds to ∠13=∠3

Alternate angle corresponds to ∠15=∠9

corresponding angle corresponds to ∠15=∠11