Pick’s theorem

What is pick’s theorem? A guy named Pick was thinking one day, what is the area of the shape had any relationship with something? So he set off to prove that the area of a polygon on a “square dot” line has a relationship with the number of dots on the interior and perimeter. And he proved himself right. I’ve worked out he answer (no internet, just pen and paper) see if you can you can work it out and explain in a comment how it is. Whether you can do it or not, share it with everyone to see if the can do it!