Two boys are stretching the dynamometer. Each exerts a force of 80 N. What does the dynamometer show?

When a dynamometer shows something, it is always acted upon by equal forces directed in opposite directions – action and reaction. His readings are always equal to one of these forces. Dynamometer boys are no exception. One of them could be successfully replaced by a hook in a wall or a sturdy post. The dynamometer will show 80 N.
At first glance, it seems that he should show 160 N. But this is possible only if the dynamometer is hooked on a fixed support, and the boys are forced to stretch the dynamometer with a force of 80 N directed in one direction.
Answer: 80 N.