Most of my code was reset. Warm Up/Moving On/Limits of Possible

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It does not compile because some variables were missing.
For some reason, the code I wrote to complete the tasks before this one was reset.
C++Basics/WarmUp/MovingOn/task/src/collision.cpp:6:24: error: ‘dx’ was not declared in this scope
6 | return (float)sqrt(dx * dx + dy * dy);
| ^~

multiple like that