you were given values for sin a and cos b ... sketch reference triangles in quad I for each angle, then determine cos a and sin bI started with

sin (α + β) = sin α cos β + cos α sin β

α = 7/25 no

B = 5/13 no

sin (7/25) cos (5/13) + cos (7/25) sin (5/13) and no

sin a = 7/25 ... cos a = 24/25

cos b = 5/13 ... sin b = 12/13

sin(a+b) = sin a cos b + cos a sin b

sin(a+b) = (7/25)(5/13) + (24/25)(12/13)