Thats a rhombus so the sides are congruent therefore <2=<4 and the hypotenuse bisects making <2=<3 . now 2 ways i can think of solving it first a triangle is 180 so 180-104= 76 to get remaining degree of the triangle and since <2=<4, 76 can be divide by 2 so thise two angles can still be congruent, therefore answer is 38.
another way is to find consecutive angle, same as above 180-104=76 but now we use <2=<3 the consecutive angle is where the hypotenuse bisects so to find <2 divide 76 by 2 and answer is 38.