The optimal objective function value of a minimization linear program problem is 18 and the optimal variable values are (X1, X2, X3) = (2.5, 0.75, 0). The dual problem's objective function is 12Y1 + 4Y2, the first constraint is unknown, but the second and third constraints are -4Y1 + 2Y2 <= 4 and 2Y1 -4Y2 <= 2. Find the solution (Y1, Y2).