Answer:
sin(A) = opp / hyp
=a/hyp. =9/15
cos(A) = adj/hyp
=b/hyp. =12/15
Tan(A) = sin(A) / cos(A)
= 9/15 / 12/15
=9/12. (you can further simplify it)
same for the B angle,
sin(B) = b/15
=12/15
cos(B) = a/15
=9/15
tan(B) = sin(B) / cos(B)
= 12/15 / 9/15
=12/9