Regardless of the integer limit, the simplex method is directly used to calculate, for example, the optimal solution x=a.b, y = c.d.
Firstly, the branch of X is divided into two cases: one is to add a constraint x≥a+ 1 on the original basis and solve it by simplex; Secondly, on the original basis, a constraint x≤a is added and solved by simplex method. Find the one that makes the optimal value smaller, and then do the same discussion on y, and you can get the integer solution.