It depends on the store. There are places where the self checkout lanes are dysfunctional and end up requiring waiting for a checkout worker (who are usually understaffed) to come and scan a code to fix it.
For the love of dog, you can't solve this problem without making assumptions that fundamentally change the answer. People are too quick to spot the first error and then make assumptions that are conveniently consistent with the correction.
You're making the assumption that the straight line consisting of the bottom edge of both triangles is made of supplementary angles. This is not defined due to the nature of the image not being to scale.
We can't assume that the straight line across the bottom is a straight line because the angles in the drawing are not to scale. Who's to say that the "right angle" of the right side triangle isn't 144°?
If the scale is not consistent with euclidian planar geometry, one could argue that the scale is consistent within itself, thus the right triangle's "right angle" might also be 80°, which is not a supplement to the known 80° angle.
This is what I was thinking. The image is not to scale, so it is risky to say that the angles at the bottom center add up to 180, despite looking that way. If a presented angle does not represent the real angle, then presented straight lines might not represent real lines.
It depends on the store. There are places where the self checkout lanes are dysfunctional and end up requiring waiting for a checkout worker (who are usually understaffed) to come and scan a code to fix it.