Pick's Theorem
https://www.math.hmc.edu/funfacts/ffiles/10002.2.shtml gives an explanation of Pick's Theorem. When all vertices of a polygon have integer coordinates, the area of the polygon is given by the formula
where is the number of interior lattice points (points with integer coefficients) and is the number of boundary lattice points.
Compute the area of the given polygon. You can check the box to see the correct answer for the area enclosed. It is possible that a non-polygon might be produced here. If so, produce a new problem and try that one.