Please help me on math and explain how to get the answer.

So here’s what i am thinking, so the right angle itself is 90°, and the top is 38°. a triangle adds up to 180° so add the 90 and 38 and then subtract it from 180. That itself gives 52°. the straight line is 180°, so you’d subtract 52° from 180° to get the outer angle, so the answer should be 128°.

No solution : there is no number of boxes that she bought