Write an equation as you read the problem n + (n+1) + (n+2) + (n+3) = 160 4n + 6 = 160 4n = 160 - 6 = 154 n = 154/4 = 38.5 and you see that there is no solution in integer numbers. It means that the problem is a FAKE : such a quadrilateral as described DOES NOT EXIST.