26.34 I believe is the correct answer
Answer:
If you draw a diagonal across the parallelogram from one vertex to the opposite vertex, you divide the parallelogram into two congruent triangles. Each triangle thus has 1/2 of the area of the parallelogram.
A box (cube) has all equal edges or sides (s), thus the volume (v) of the cube is:

So since each side or edge around is 3 in, then the length around the square bottom of the box = 4×3 = 12 in
138° + w° = 180° (sum of angle on a straight line)
w° = 180° - 138°
w = 42
19° + x° + w° = 90°
sub. in w=42,
19° + x° + 42° = 90°
x° = 90° - 19° - 42°
x° = 29°
x = 29